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No Gigabit ethernet on 2009 iMac

I have the same problem with iMac Gigabit connection. Check:

Disconnect ethernet cable from rear panel on iMac (i5 2.7 GHz) and connect cable to MacBook Pro running either 10.6.8 or 10.9.5 or 10.10.2. Network end is DrayTek router 2820 with 1G output. ifconfig on Macbook shows: "auto-select (1000baseT) full duplex, flowcontrol". Router ethernet socket lamps confirm connection at 1000baseT.

Manually setting iMac to 1000baseT, full duplex flow control results in "ethernet not plugged in" as reported elsewhere. iMac ethernet card by Broadcom 57765-B0 which supports 1000baseT.

This confirms many reports on this thread that (a) this is not a cable fault (b) this is not an individual iMac fault (c) this is not an OSX specific fault but (d) a widespread configuration problem on iMacs, possibly a kext problem, but certainly an Apple problem.
 
DeputyRob said:
No. The iMac will NOT render 1000baseT (Gigabit) Ethernet. I do back-to-back testing and the iMac drops to Fast Ethernet every time. If you do an internet search you'll see numerous people have reported this issue but not one single one of the threads on the issue provides a solution. Either the original poster simply disappears or respondents blame peripheral equipment (routers, cables, etc) instead of the iMac.

----------

When the settings are like this, it provides (obviously) Fast Ethernet speeds.
Image

But if I change the speed setting to 1000baseT, I lose connectivity with the following message (enclosed in red, below):

Image
Click to expand...

Hi OP,

Did you have an opportunity to try an SMC/PRAM reset?
 
Thanks for response. No, I haven't tried an SMC/PRAM reset. I notice several other threads considering patches to AppleBCM5701Ethernet kext which is the NIC driver. It is not obvious that these work on the Broadcom 57765 card. This problem is also reviewed on Apple Support forum - with no solution
 
jmnrmn said:
Thanks for response. No, I haven't tried an SMC/PRAM reset. I notice several other threads considering patches to AppleBCM5701Ethernet kext which is the NIC driver. It is not obvious that these work on the Broadcom 57765 card. This problem is also reviewed on Apple Support forum - with no solution
Click to expand...

Okay. What about through Safe Mode (hold Shift on Startup)? You may get a lot of graphical glitches but that's normal through Safe Mode. Could you try the Ethernet there?

Also, what about through the recovery (hold Cmd+R on startup)? In OS X Utilities there's an option for 'Get help online'. This would at least allow you to open up an Internet browser and then run a Speedtest or something. If the speeds are considerably quicker through the recovery partition then this would indicate a software issue.

A few other suggestions, if I may:

- Verify Disk through Disk Utility - if it requires repair, you can do that through the recovery partition
- Repair Disk Permissions through Disk Utility
- Check HDD SMART data by downloading SMART Utility: http://cloudfront.volitans-software.com/smartutility312.zip
- And aforementioned SMC/PRAM reset

If the issues persist after SMC/PRAM, or the above troubleshooting steps, would it be possible for you to kindly try the following:

- Download a dmg of Mavericks
- Install Mavericks to external drive (external HDD or even a 16GB pendrive)
- Boot into new Mavericks install (hold Alt on startup with it plugged in) & try Ethernet again

I really appreciate this is a lot to do but it will allow us to diagnose if the issue is related to the software or the hardware. If the high-speed Ethernet works on the external Mavericks install, then we definitely know it's something software related. If it doesn't work on Mavericks (or an earlier install) then it could indicate an additional problem.

I don't believe Mavericks is available on the App Store any more so I'd suggest torrenting a version (as it's a free application and Apple no longer supply it, there's nothing illegal about it).

Please keep us posted, I can't begin to imagine how frustrating this problem is for you.
 
I have just run four tests - and then I'll get back to your suggestions.

1. Boot up with my external drive carrying 10.10.2. This uses a later version of AppleBCM5701Ethernet.kext but 1G connection fails.

2. Boot up in single user mode (CMD+S) without further commands. Router LEDs indicate connection in 100BaseT. 1G fails.

3. Shutdown. Router LEDs now off. Hit the power button. As the startup sound is heard router LEDs immediately show connection in 100BaseT. This will be before any kexts are loaded. This is the result of immediate handshake between the NIC and the router port.

4. Repeat test 3 but with the MacBook Pro. As the startup sound is heard router LEDs immediately show connection in 1000baseT. Again, this is the result of immediate handshake between the NIC and the router port.

From this I conclude that the failure to connect as 1G on the iMac is most likely a deficiency in the NIC firmware and is not a problem with the ethernet kext which could only be loaded once the boot-up procedure had gone through some initial steps and could not have been loaded within 1 second of power-up.

As for speed tests, these are probably not relevant given the current state of my ADSL connection. I had noticed that the 1G LED was not showing on the router port and wanted to chase this. Was the router port not working? Was it a CAT 5 cable problem? A software problem? I will soon have a fibre (instead of copper) broadband so having the 1G would be nice but not a show-stopper.

Being able to compare the iMac with the MacBook Pro is, in my view, fairly convincing that this is a firmware problem.

Your comments are appreciated...
 
An addition: Perhaps the AppleBCM5701 is installed in the kernel originally (kext - kernel extension). At boot time dmesg is interesting:

BCM5701Enet: Ethernet address c8:2a:14:21:72:0b
...
AppleBCM5701::selectMedium - gigabit, full duplex, EEE disabled, flow control required

so the router's 1G port is sensed correctly and an attempt is made to connect but 9 lines later this appears in dmesg:

AppleBCM5701::selectMedium - 100mbit, full duplex, EEE disabled, flow control required
Ethernet [AppleBCM5701Ethernet]: Link up on en0, 100-Megabit, Full-duplex, Symmetric flow-control,

where without errors being provided, the attempt to connect at 1G is abandoned and 100mbit is attempted successfully. There are no console messages to explain the 1G connection failure.
 
Hi jmnrmn, this is already well beyond my expertise. From what you've described I think you're absolutely right in saying it's a firmware issue.

As the onus is on Apple, I imagine the only thing you can do from here is give them a ring and outline what you've already tried, or possibly pop into an Apple Store to see what they can do to to escalate the complaint.

Even if you're out-of-warranty, it should still be their responsibility to resolve an issue as bad as this.

I'm sorry I couldn't be of more assistance.
 
Thanks for the reply. I had to make one further test. Today I borrowed a length of ultra-high quality cable: Nordx/CDT IBDN GigaFlex PS6LX Modular Cord Solid Core CAT 6 cable.

Instant connection at 1000baseT! I thought my previous cable was good enough since the MacBook connected at 1G. Shows that the BroadCOM NIC wants the very best.

Problem finally solved...
 
keysofanxiety said:
Hi OP,

Did you have an opportunity to try an SMC/PRAM reset?
Click to expand...

:D

I believe I am the OP here, not jmnrmn. But I'm glad jmnrmn chimed in because he seems to have tracked down the problem.

The question now, it appears, is where this particular cabling is sourced. I found numerous references to it but its availability appears to be for bulk purchasing only. I'll call the manufacturer and advise if jmnrmn doesn't have a supplier.
 
Thanks DeputyRob. I was given a short length of good quality CAT 5E cable which was as good as the NORDX CAT 6 PS6LX cable and this also worked. The connection from the iMac to the router is solid 1000BaseT. Thank you for your offer to find a source of NORDX cable - appreciated.

JMN
 
Got it working on my 2009 iMac 27" i7

Well I too had this problem. I thought the problem might have been that there was something I needed to activate or whatever to enable the 1000 Mbit/sec connection.

After reading this thread I was a little concerned. Well to make a long story short . . . I traced the problem to a bad cable between my iMac and the wall jack I put in. I just need to either put new ends on the existing cable or make a brand new cable. Since the 8 pin modular connectors (aka RJ-45's) are a bit cheaper than the roughly 16' length of cable I need I will likely replace the ends one at a time first.

I just wanted to let everyone else know that in my case the problem was a bad cable. Using a store bought cable (that I had lying around from before I purchased a crimping tool) I was able to get the 1000 Mbit/sec lights on my router to light up with this late 2009 27" i7 iMac no problem. Since my Internet connection is less than 100 Mbit/sec (it is 75/75 Mbit/sec) I have no way right now of testing the speed. After I get my NAS built in the next week or two . . . I should have a much better idea if I am seeing maximum throughput. I suspect I will be fine.
 
GaryE said:
Got it working on my 2009 iMac 27" i7

Well I too had this problem. I thought the problem might have been that there was something I needed to activate or whatever to enable the 1000 Mbit/sec connection.

After reading this thread I was a little concerned. Well to make a long story short . . . I traced the problem to a bad cable between my iMac and the wall jack I put in. I just need to either put new ends on the existing cable or make a brand new cable. Since the 8 pin modular connectors (aka RJ-45's) are a bit cheaper than the roughly 16' length of cable I need I will likely replace the ends one at a time first.

I just wanted to let everyone else know that in my case the problem was a bad cable. Using a store bought cable (that I had lying around from before I purchased a crimping tool) I was able to get the 1000 Mbit/sec lights on my router to light up with this late 2009 27" i7 iMac no problem. Since my Internet connection is less than 100 Mbit/sec (it is 75/75 Mbit/sec) I have no way right now of testing the speed. After I get my NAS built in the next week or two . . . I should have a much better idea if I am seeing maximum throughput. I suspect I will be fine.
Click to expand...

I just wanted to chime in here even though it's well after the fact. The conclusion here is arguably wrong. I wouldn't call it a "bad cable". There's something with OSX that is very wrong.

Using the same cards and same switches with FreeBSD, the cards connect at 1000baseT quite easily and regularly with long 15ft home depot cat5 cables. And I mean easily; never get 100baseT connection. With osX, I had to use a short cat6 cable to get it to connect at 1000baseT. This was the case with 3 different cards: a realtek, a Yukon and an e1000 Intel card. So it seems that the problem is in the OS and not the driver. I'm not an OSX internals guy, but it seems unlikely that drivers ported from linux would themselves all have the same unusual problem. Modern cards are very good at negotiating and you shouldn't need cat 6 cables to connect at a gigabit unless you're using 50ft cables. Even then a newish e1000 card would connect at 1000baseT. Even the $20 gig switches are all very robust at negotiation. I have a mishmosh of cables in my lab and we haven't had a negotiation problem in years; except with MACs.
 
Just installed fiber Giga internet to the home.

mid 2010 21.5" iMac (Yosemite) would not connect via a 25' Cat6 cable to a Netgear R6300v2. It would only handshake at 100baseT. Worked great at 100mbs however, so I knew it wasn't the card/firmware/OS, but what about the cable?

Changed to a higher quality 10m Vandesail CAT7 cable off Amazon. BINGO! The Cat7 cable has much better shielding between each pair and better connectors compared to a Cat6/5e/5.

My guess is that the Broadcom 5764-B0 NIC in the iMac is very picky about it's 1000baseT connection.

Getting a solid 700-950mbs!
 
shooterEET said:
Just installed fiber Giga internet to the home.

mid 2010 21.5" iMac (Yosemite) would not connect via a 25' Cat6 cable to a Netgear R6300v2. It would only handshake at 100baseT. Worked great at 100mbs however, so I knew it wasn't the card/firmware/OS, but what about the cable?

Changed to a higher quality 10m Vandesail CAT7 cable off Amazon. BINGO! The Cat7 cable has much better shielding between each pair and better connectors compared to a Cat6/5e/5.

My guess is that the Broadcom 5764-B0 NIC in the iMac is very picky about it's 1000baseT connection.

Getting a solid 700-950mbs!
Click to expand...

Got the same issue will buy that cable and try it out, cross fingers
 
Just a heads up, as I've seen this a couple of times before. It isn't so much the quality of the cable, but the quality of the connectors. The iMac's ethernet port (before they went on a diet) isn't the best quality, and over time the pins inside the port bend slightly out of shape, meaning that you don't get a clean connection.

I've also solved it in the past by re-crimping a cable but pressing incredibly hard on the connector, almost to the point of it breaking.
 
cececmf said:
Received the cable, didn't make a difference :(:mad:
Click to expand...
Did you try:
Restarting your Mac?
Reset the PRAM?
Adding a new location to your Network prefs, then set up your ethernet for that new location?
Do you have a router/hub that does, in fact, support Gb (or higher?)
Restart your router, if you have access to the router.
 
DeltaMac said:
Did you try:
Click to expand...
Restarting your Mac? Yes :) first thing I did
Reset the PRAM? no I didn't will google it to see how to do that
Adding a new location to your Network prefs, then set up your ethernet for that new location? Yes
Do you have a router/hub that does, in fact, support Gb (or higher?) Yes DSL-AC68U Asus
Restart your router, if you have access to the router. Done that already, I even reset it to default factory settings just in case.

When I unplug the ethernet from my mac and plug it into my macbook pro I get straight away 1000mbps so it's not a cable or router issue. Also previously I had 1000mbps with this iMac for years.
 
cececmf said:
Restarting your Mac? Yes :) first thing I did
Reset the PRAM? no I didn't will google it to see how to do that
Adding a new location to your Network prefs, then set up your ethernet for that new location? Yes
Do you have a router/hub that does, in fact, support Gb (or higher?) Yes DSL-AC68U Asus
Restart your router, if you have access to the router. Done that already, I even reset it to default factory settings just in case.

When I unplug the ethernet from my mac and plug it into my macbook pro I get straight away 1000mbps so it's not a cable or router issue. Also previously I had 1000mbps with this iMac for years.
Click to expand...

I have tried to reset the PRAM and didn't make a difference
 
Check the ethernet port on your iMac that the pins are in a good position to connect, and that the connector is clean.
Try another cable.
Check the hardware connection reported by the System Information when you are booted to another system - you can try booting to your Recovery system, then open the System Information in the menu.
 
I have plugged my flatmate thunderbolt > Ethernet and that works ! get 1000mbps so it must be a port issue or driver issue on my iMac

THUNDERBOLD ADAPTOR:
2015-09-0308.56.12pm.png

I took picture of my port, doesn't look like any of the connectors are damaged:

IMG_3409.jpg
 
After getting 2010 iMac to work by upgrading to a better ethernet cable (Cat7), I started noticing that the connection would revert to 100 at random times (or so I thought). Turns out I had it configured to SLEEP after 8 hours and sure enough every time it went to sleep, it would dump the 1000mbs and change to 100. Now I continue to maintain a 1000mbs connection.

Have you switched ports in the router and/or tried a shorter cable?

Is your router IPv6 set up correctly? Seems like it could be a router problem in its handshake with the Mac?
 
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