Network problems (lost WAN, but not LAN)

[macstatic]

I've set up a wired home network with a couple of (sometimes three) Macs and other stuff, and now and then we lose Internet access. Using the OSX IP widget (in two instances) we can see the LAN and WAN IP addresses. When Internet is lost we usually find that the WAN address is gone.
After a while it's back again. I don't know if the problem applies to both computers at once (typically I check the IP address on the second computer, but when I see that working I also see that the first computer has gone back online again. Also, we usually don't use both computers at once, so this is quite frustrating to figure out).

We've just (a couple of days ago) received a new cable modem as the previous one stopped working, so I'm surprised this is still happening. I've been unplugging/replugging different ethernet cables whenever this happens, and all of a sudden it works again, so I've assumed there's a bad cable somewhere.

But.... with a bad cable, wouldn't I lose ALL network (LAN and WAN) at once?

The network is set up like this, in the following order:
1) Cable modem (coaxial cable into wall-socket, Ethernet out)
2) Cisco RVS-4000 (4-port Gigabit router with VPN)
3) Zyxel GS1100-16 (16-port unmanaged switch)
4) Macs and other Internet-related gear

Both Macs are running OSX 10.9.5

 

[techwarrior]

Sounds like the router is flaky. Do you have an old router you can use to test this theory?

Also, did you register the new modem with the ISP?

The only flaky ethernet I would be suspicious of is the modem <> router.

 

[macstatic]

So can I rule out any bad ethernet cables/sockets, or is it still possible that LAN can be received (and fully working) while WAN is inaccessible?

Actually I did receive a router from the Cable-Internet provider but I've never used (I bought the Cisco RVS-4000 since I needed multiple ports, which the other one didn't have). However, since then I've needed even more ports, so I added the Zyxel switch, which means I really only need a basic router anyway, so if the Cisco router acts up I can replace it with the simpler one.
But for the time being I've reset it to its factory default values and will see if that changes things.

Register the new modem with the ISP? The instructions (from the provider) didn't say anything about that. Only a simple "how to" for connecting it and awaiting the "Online" LED to light up. This LED was still lit when the WAN problem came up though, so your theory sounds right.

 

[techwarrior]

So can I rule out any bad ethernet cables/sockets, or is it still possible that LAN can be received (and fully working) while WAN is inaccessible?

Actually I did receive a router from the Cable-Internet provider but I've never used (I bought the Cisco RVS-4000 since I needed multiple ports, which the other one didn't have). However, since then I've needed even more ports, so I added the Zyxel switch, which means I really only need a basic router anyway, so if the Cisco router acts up I can replace it with the simpler one.
But for the time being I've reset it to its factory default values and will see if that changes things.

Register the new modem with the ISP? The instructions (from the provider) didn't say anything about that. Only a simple "how to" for connecting it and awaiting the "Online" LED to light up. This LED was still lit when the WAN problem came up though, so your theory sounds right.

ISPs generally have to provision modems for network access. Kind of like cell phones, they look at the mac address of the modem to determine if it is authorized for use n their network.

If the WAN port is not holding an IP address, it suggests the modem and\or router is not stable. lan segments will not effect this.

 

[macstatic]

I suppose the modem, being delivered by the network provider and seemingly a custom made unit probably has that info already built in.

I'll see how it goes after now having reset the router to its factory defaults, then replace it with the other router if it proves to be unstable.

As mentioned we have multiple Macs connected to the same (wired) network, and I seem to recall that while a Mac Mini had lost its WAN, the MacBook Pro still had it.
It could be that the Mac Mini all of a sudden had gotten it back when I checked the Macbook Pro, but is it possible for one computer to lose WAN (but keep the LAN) while another computer on the same network has both LAN and WAN? This is what puzzles me -because if the modem or router is at fault, surely all computers would lose LAN at once, right? And with a broken cable or a socket having contact problems I would lose both LAN and WAN simultaneously for that specific computer?

 

[jeyf]

... all of a sudden had gotten it back when I checked the Macbook Pro...

so you have wifi? Try a free ios app 'Fling', nice tool giving you a bigger total view of things.

pull up the cable modem internal page with the mac that lost internet to see if anything changed
your router has an internal page? if yes see if there is a lan side list of routed devices
all devices on board with the start adr and end adr of the lan routing range
call your isp and see if the can ping your cable modem, have them give it a reset

 

[macstatic]

so you have wifi? Try a free ios app 'Fling', nice tool giving you a bigger total view of things.

No, generally we're keeping to a wired network, but occasionaly we do WiFi Internet sharing from one of the Macs if we need that (iPad etc.) by using the "Sharing"-"Internet Sharing" system preference). The problems with lost WAN have of course been reflected to the iPad having lost Internet acess as well when the Mac in question has lost it. Thanks for the tip though -I'll have a look at that IOS app.

pull up the cable modem internal page with the mac that lost internet to see if anything changed
your router has an internal page?

I'm not sure what you mean. Are you referring to the configuration option via a web browser that comes up when you enter the appropriate LAN address for the unit (192.168.x.x)?

I don't know of any such configuration for the modem, and there wasn't any manual with it either (just a quick connection guide). The only thing I know to configure is the Cisco router, and that's now been reset to its factory defaults.
The network switch doesn't have any configuration options either as it's "unmanaged".

if yes see if there is a lan side list of routed devices
all devices on board with the start adr and end adr of the lan routing range
call your isp and see if the can ping your cable modem, have them give it a reset

There's a bunch of stuff like that when I log into the router configuration, but I really don't know how to interpret most of it.
I'll see how things work out in the next few days and get back here if we get any more "hickups".

 

[jeyf]

good for you on going hard wire ethernet. I assumed you had the newer MBP w/o the ethernet connector. No big but applications like fling give you an extra tool to see whats going on. I like the ios Fling and its 4free. there are macOS based applications too. If all else failed your iPhone will still be running and you can use it to diagnose the network problem.

yes your cable modem and likely your router have an internal web page.

In my area the Comcast Cable outside wiring is very old. I got a cable modem when I first moved in and it would only run a month than brick it self. I could do nothing on my side. I had to call Comcast to get it reset. I thought a lot of things till i talked to my neighbors who were having the same issues. I switched my internet provider to fiber to the house.

Next time this happens to you consider calling the internet provider and see if they can ping your cable modem box. They should be able to even describe the router connected to the cable modem. Have them reset the cable modem. Ask them if all those biking led's on their modem can indicate anything other than its near xmas time. So next time things go bad you can at a glance determine if the cable modem is talking to the internet provider.

-go through all your ethernet and cable TV wiring and verify all the connections are as expected.
-avoid having the internet provider send a repair team, they are expensive.

not related to your issue but:
avoid double routing
verify your cable modem has routing turned off and is in pass through mode.
If when you use wifi verify it also has routing turned off and is in pass through mode.
avoid daisy chain routers together 4extra ports
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