mac_in_tosh

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This has started recently on my MB Pro running Big Sur 11.3.1 - I open Firefox or Safari and the home page doesn't load nor does any other site. A progress bar starts but stalls. The same thing happens in other accounts on the same machine. Sometimes if I log out of the account and log back in it works but more often I have to do a Restart, after which things work as expected. Just now I first checked my email, which responded quickly, but then the browsers didn't respond, with Firefox timing me out.

I'm on WiFi using an Airport Extreme Base Station that is connected by ethernet to a FIOS modem. Just looking for some suggestions as to where the issue might lie and what I might check. Thanks.

EDIT: I didn't mean to imply that this happens every time. It's just occasional.
 

chown33

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The next time it fails, run Wireless Diagnostics:

Actually, practice using WiDi now, so you know how to use it when there's a failure.

It could be almost anything, such as an issue with interference, signal strength, DNS, or various other things.
 
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mac_in_tosh

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I'd run speedtest first to determine if your network is responding.
The problem is that when the issue occurs the speedtest website won't load.

Here is what I've done when the issue occurs, based on suggestions so far:

o ran WiFi diagnostics - it didn't find any problems
o connected directly to ethernet with WiFi off - issue persisted
o again verified that the issue is not limited to one account

With the most recent occurrence earlier today, logging out didn't help but once again after rebooting everything worked as expected.

One other thing, I am running Malwarebytes Premium but I turned off "Malware Protection" and "App Block" while experiencing the issue but it didn't help (I think these are real-time processes separate from the periodic scan).

Any other suggestions?
 
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chown33

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I think a next step will be to distinguish name lookups from basic connectivity (routing). It might not be the very next step, but if you have the procedure ready to go, you can try it at the next failure.

Checking basic connectivity will probably use the 'ping' and 'traceroute' commands. Those used to be available in "Network Utility.app", located in /Applications/Utilities. I've read that Big Sur (or perhaps earlier) no longer has Network Utility, so a Terminal command line is likely going to be needed.

The 'ping' and 'traceroute' should refer to hosts using their IP addresses, not their DNS names. If you used DNS names, then the first thing that happens is a DNS lookup, which means you can't really distinguish name lookup failures from basic connectivity failures.

A useful target host is the example host example.com. It has several alias names, including example.org and example.edu. An example command that pings it 5 times using its DNS name:
Code:
ping -c 5 example.edu
PING example.edu (93.184.216.34): 56 data bytes
64 bytes from 93.184.216.34: icmp_seq=0 ttl=57 time=20.297 ms
64 bytes from 93.184.216.34: icmp_seq=1 ttl=57 time=20.077 ms
64 bytes from 93.184.216.34: icmp_seq=2 ttl=57 time=20.288 ms
64 bytes from 93.184.216.34: icmp_seq=3 ttl=57 time=20.217 ms
64 bytes from 93.184.216.34: icmp_seq=4 ttl=57 time=19.747 ms

--- example.edu ping statistics ---
5 packets transmitted, 5 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 19.747/20.125/20.297/0.205 ms
The 1st line shown is the command to paste into a Terminal window. The remaining lines are ping's output.

You can see that the first thing it does is lookup the name to get an IP address. That's a 56-byte packet, and resolves the name to the IP address 93.184.216.34. The remaining lines show each ping, followed by summary data.

If you used example.com, you'd notice it resolves to the same IP address.


You should also do a ping on your local router, so you can tell whether traffic is even getting that far.


The command to do name lookups is 'dig'. It's more complex than ping, so it's best if you read its man page. Same goes for 'traceroute'. Read them with man dig and man traceroute in a Terminal window.

I recommend practicing different commands until you have one that produces desired info, then storing them in a plain text file, which you can edit in any text editor, including TextEdit. This lets you save predetermined and known-good command-lines in a file, open it in TextEdit, then paste the lines into a Terminal window. Saving them makes duplicating commands exactly at any future time very easy. No remember and type, just copy and paste.


This is a simplified description, and may contain subtle mistakes that would horrify a punctilious network engineer. I'm just describing a few brief things I've used in the past with some success.
 
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HDFan

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The problem is that when the issue occurs the speedtest website won't load.
Speedtest has an app that you can run that is standalone. Sound like you don't have a network, or maybe a really slow one.
Checking basic connectivity will probably use the 'ping' and 'traceroute' commands.

A network problem is causing your browser issues. ping and traceroute can help diagnose.
 
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mac_in_tosh

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I really appreciate everyone's help in this matter. A lot of chown33's post is over my head but, as outlined below, I did use some of it.

I did the following while the browsers were not responsive:

o I had my iPad sitting next to the Mac and ran Safari on it, using the same WiFi as the Mac uses. Websites loaded quickly; no sign of a problem.
o On the Mac, I open the Mail app and it responded quickly (telling me no new mail).
o I ran the Speedtest app on the Mac and was getting the expected speeds.
o I opened Terminal and entered ping -c 5 example.edu and got the results shown above (5 packets transmitted, 5 packets received).

These results are telling me that it's not a network issue, but something specific to the Mac and in particular to the browsers.

Let me throw out an observation - I think that the problem generally arises while I am at the Yahoo site (using Firefox - it's the home page for that browser). For instance, today I woke up the Mac, checked Mail, ran Safari and all appeared normal. I ran Firefox and when I clicked on the mail icon things hung up - neither Firefox nor Safari would then load pages. Things seemed to resolve after a while without having to restart.

So could it possibly have something to do with Yahoo's website? Could that be doing something that affects how Firefox and Safari load web pages that gets resolved with a reboot?
 
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mac_in_tosh

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It happened again. I was cruising along on the internet, went to the Yahoo home page using Firefox and it got hung up loading the page completely, after which Firefox and Safari would not load anything, even in another account on the Mac. Speedtest was normal; the terminal ping command gave the expected results. Once I rebooted, the browsers were working again.

Short of solving this issue, is there something I could do instead of rebooting that might serve the same purpose, some way of clearing whatever is hanging up the browsers?

Thanks.
 
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HDFan

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You are saying that when the browsers hung speedtest and ping worked?

What were the speedtest values?

If you boot into single user mode does the same thing happen?
 
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Toutou

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is there something I could do instead of rebooting that might serve the same purpose, some way of clearing whatever is hanging up the browsers

I've been having the same problem lately and I believe it has something to do with the macOS DNS resolving mechanism (translating hostnames like 'example.com' to IP addresses like 93.184.216.34). That would explain the fuzziness of the issue, like that sometimes pings to already resolved hostnames continue to work but browsers can't load new pages.

What 100 % works for me is this command, in Terminal:
Bash:
sudo killall -HUP mDNSResponder

The "sudo" part (do as superuser) will ask you for your password and it will not show anything as you type, no asterisks, nothing. That's normal.

What the rest of the command does is that it sends the "hang up" (HUP) signal to the macOS' mDNSResponder process which forces it to restart. I have no idea why this works, because mDNSResponder should only be responsible for mDNS, a special mechanism that's slightly different from normal DNS, but I can only assume that the mDNS and DNS handling is somehow intertwined inside macOS that one can either block another or one can restart another.
 
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Ruggy

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It's very likely the DNS servers.
That means it's probably your IS provider.
When the DNS servers are saturated then things come to a crunching stop until the traffic reduces a bit.
Mail which uses FTP still (I think) tends not to be affected.
To test this, you manually select public DNS servers and see if it works faster.
I would recommend Cloudflare as being fast and secure but you can use Google servers or Open DNS.
In order to try this you go into your network configuration via the wifi icon in the address bar>advanced and navigate to the tab for DNS
For cloudflare you would add the servers
1.1.1.1
1.0.0.1
You can give it a go and see if things get a bit snappier.
For speed testing try Fast.com
 
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mac_in_tosh

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You are saying that when the browsers hung speedtest and ping worked?

What were the speedtest values?

If you boot into single user mode does the same thing happen?
Speedtest values were ~80 Mbps up and down, as expected.

I had to search single user mode to even know what it is. Looks like something beyond my capabilities.
 
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mac_in_tosh

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Update - I believe that I've narrowed the issue down to when the Yahoo home page loads as that is the only time it arises. It's possible that it's also a Yahoo/Firefox thing as today the Yahoo page hung several times using Firefox (requiring one or more log outs to get things working again, and again Speedtest was normal, the App Store worked fine, etc.) but when I went to Yahoo using Safari it worked, at least the 2 or 3 times I tried it.

Come to think of it, when on my iPad I've noticed that occasionally Yahoo would freeze the Firefox app. Luckily there all I have to do is quit the app and restart it.

Of course it may not be Yahoo per se but the fact that its home page has a lot of things to load and that somehow hangs up the browsers.

I appreciate @Toutou's advice to try sudo killall -HUP mDNSResponder but as he/she is not sure of why it works perhaps someone can comment on the advisability of using it.
 
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mac_in_tosh

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I don't know if anyone is still following this thread, but I wanted to give an update and see if anyone could guess at an explanation.

I've continued to access Yahoo using Safari for several days without any incident (until yesterday when browsers got locked up once but that may have been unrelated). So it strongly suggests that the combination of Firefox and Yahoo (where I have email) is what caused the frequent browser lock ups that I had been experiencing. As mentioned in my last post, it also happens, but less frequently, when accessing Yahoo using Firefox on my iPad.

What do you think is the issue such that once Firefox locked up it affected Safari also, even in other accounts on the Mac?
 
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MacCheetah3

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This is a doozy. However, after reviewing everything, I have a partial theory. Try going to http://example.com in one of your browsers after visiting Yahoo or whenever they stop functioning. I know you already used the Ping tool on it but bear with me.
 
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mac_in_tosh

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This is a doozy. However, after reviewing everything, I have a partial theory. Try going to http://example.com in one of your browsers after visiting Yahoo or whenever they stop functioning. I know you already used the Ping tool on it but bear with me.
Thanks for the suggestion. After reading your post, I went back to accessing Yahoo with Firefox and the very first time that I did so it locked up trying to load the Yahoo home page. Safari was also locked up in that account on the Mac. I entered http://example.com in the address bar of both browsers and it didn't load. What happens in these instances is that the progress bar starts, as if a web page is loading, but then it stalls.

I switched to the other account on the Mac and both browsers were similarly locked. In Safari it did go to the example.com web page, but not in Firefox. However, the link to More Information there didn't work in Safari.

I had to reboot to get the browsers to work again.
 
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MacCheetah3

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Okay.
🤔
I don’t know if that debunks my theory or not.

Here was my thought process:

1) You removed and added network (e.g., Wi-Fi) connections, the Mail app works, and you can ping example.edu (i.e., a domain), it’s probably not a DNS problem.
2) Other devices can access the Internet when your Mac cannot
3) It’s apparently a system level problem as you state the issue spreads across user accounts
4) You mentioned the problem begins after accessing Yahoo email via their Website

Of course, as it should, Yahoo uses a secure HTTP connection. 💡 Perhaps the way Yahoo’s servers are going about establishing or relinquishing the connection stalls out — I admit to not knowing what specifically this is — whatever local service/process manages those connections. Normally a positive, almost every site nowadays establishes a secure connection immediately, on every page (not just for logins and other forms). Therefore, if your problem is HTTPS connections getting jammed up, it would cause nearly every site to be inaccessible. That fact also makes verification more challenging. While trying several sites, I remembered the example domain. Sure enough, when I visited, it was “not secure.” That’s why I suggested you try it when the Web browsers stop properly functioning.
 
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chown33

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You could try this in a Terminal window next time it stalls out:
curl -v http://example.com/

Type it exactly as given, or paste it into the Terminal window.

I suggest trying the command now, so you know what it looks like. The output will begin with curl's verbose diagnostics, including details of how it's connecting, what it's sending as the HTTP request, and the headers of the reply. After the last header output (lines starting with <) will be the actual HTTP content, which consists of HTML and CSS in a single page. That's followed by curl's final diagnostic output closing the connection.

If you drag-select in Terminal, you can then copy the output and paste it into a TextEdit document, so you can use it as a reference when you try curl again after a stall-out.
 
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mac_in_tosh

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You could try this in a Terminal window next time it stalls out:
curl -v http://example.com/
It didn't take long for Firefox/Yahoo to hang things up - it did so the second time I tried.

With no issue, I ran you command and got a lengthy output. When the issue was present, it only got to the seventh line in the output, > Accept: */*, and then nothing followed, just another >.

Things seemed to get back to normal on their own after a minute or so, without my having to reboot, and then the command once again led to the lengthy output.

Does this tell you anything?
 
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chown33

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It didn't take long for Firefox/Yahoo to hang things up - it did so the second time I tried.

With no issue, I ran you command and got a lengthy output. When the issue was present, it only got to the seventh line in the output, > Accept: */*, and then nothing followed, just another >.

Things seemed to get back to normal on their own after a minute or so, without my having to reboot, and then the command once again led to the lengthy output.

Does this tell you anything?
It might. I'd need to see the actual output from the malfunction, along with the output from when it worked.

You can click-and-drag the cursor in a Terminal window to select text. Then copy and paste it into a reply here, between [CODE] [/CODE} tags.
 
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