2021 iMac M1 Ethernet connectivity woes (solution provided)

Question

Level 1

36 points

2021 iMac M1 Ethernet connectivity woes (solution provided)

The following issue is completely resolve but I'm posting this here for 2 reasons. 1) I'm curious to see if anyone else has experienced this issue and 2) if so, I hope this post helps.

Backstory

This 2021 iMac was purchased as an upgrade to my 2015 iMac. The 2021 iMac has replaced the old 2015 iMac and, as such, is taking up the space of where the 2015 iMac was. Point being, the 2021 iMac is using the same ethernet port as the 2015 iMac was using.

The Issue

I have a status bar widget that reports my IP address that triggered me to investigate what ended up being my ethernet connection dropping during large file tranfers. I opened 🍎 -> System Preferences -> Network during a large file transfer (a 10GB video file) and sure enough, the ethernet connection was dropping between green dot "connected" to red dot "not connected" but there wasn't any sort of pattern. Sometimes it would drop only at the end of the file transfer, other times it would drop/reconnect throughout the transfer. All transfers were successful, albiet, slow due to drops.

The Troubleshooting

I spent 2 days trouble shooting everything at the phsycial layer of my network. All network cables were checked. My last effort was connecting both iMacs and a 10GB file transfer was successful without any drops.

The Culprit

Because the 2021 M1 iMac's optional ethernet adapter is housed in the power brick, I theorize that the amperage of the data payload coming from the iMac to the switch, couple with the rest of network traffic, was causing the port on the switch to drop the connection. The switch, a Netgear GS316, is powered by a 12v, 1a power supply/cable combo which I believe is unable to provide the peak power demand from the network.

The Solution

I went out an about an unmanaged switch (Netgear JGS524) with a built in power supply. I swapped out the switches and the ethernet drops the 2021 iMac was experiencing stopped. Several test transfers later and I felt confident I had solved the issue. The golden standard of troubleshooting is being able to replicate the issue. I swapped out the new switch with the old and my connectivity issues returned.

Conclusion

Again, I did not post this looking for help as the issue is already resolved. I'm just curious to see if my issue is shared by anyone else.

Posted on Jun 9, 2021 9:12 PM

Reply

Answer 1

Top-ranking reply

shanafme24

Level 1

4 points

Jun 30, 2021 4:31 PM in response to xdracco

I wish I would have seen this about a week ago.

I had the exact same problem. New iMac (with Apple Silicon) wired into a Netgear GS316 unmanaged switch. I've noticed that the network would act goofy at times, large file transfers would just stop, my network Time Machine backup would never finish, etc...

I started a continuous ping test and then try to move a 4 GB file from my NAS over to the iMac. The transfer would start and get about 20% complete before the ping would start timing out and the network connection would start to turn off and then on again.

Ended up calling Apple and they suggested the route that you went, taking the switch out of the picture. Fortunately, I had 2 smaller switches I could test with, and there does in fact seem to be an icompatibility between the new (2021) iMac and the Netgear GS316. I called Apple back and told them about the issue and they said they would forward it on to the engineering team, but who knows....

Anyway, I'm glad to see that I wasn't the only one with this issue. Looks like it is time to shop for a new 16-port switch.

Reply

Answer 2

xdracco Author

Level 1

36 points

Jun 30, 2021 7:30 PM in response to shanafme24

oh good. glad to see i'm not the only one who experienced the issue. at one point, i was absolultely dreading the idea of having to fish a new cable through my wall. that was my nightmare scenario. thankfully, i didn't come to that.

one thing to keep in mind. the smaller switches (seemingly 16 port or smaller) use less power. I ended up having to go with a 24 port switch to make sure it had enough power supply. I ended up with the netgear JGS524 which had a $150 price tag. it's been 3 weeks now and not a single issue since.

whether it's a layer 2 incompatibility btween imac and gs316 or something dumb like my theory.. like you said... who knows...

salud!

Reply

Answer 3

Jul 2, 2021 11:31 AM in response to xdracco

I just picked up a D-Link 16-port switch (model DGS-1016S) to replace the Netgear GS316. Initially testing looks favorable. Just transferred several 4GB files and there were no drops in the connection. I'll do some more testing this weekend, but it is looking good.

Reply

Answer 4

Jul 8, 2021 12:44 AM in response to xdracco

Thx xdracco for your thread here!

I have now a possible way to find a solution. I am using a NetGear GS308P and had the feeling, that the router is the problem. But no idea why. Because all other devices just work fine.

I will connect the MBP direct to my router and will monitor this issue further.

Reply

Answer 5

xdracco Author

Level 1

36 points

Jul 8, 2021 8:07 AM in response to joachim_79

i honestly really doubt the router is the issue. if it were the router, all devices that the router is connected to (via the switch) would lose connectivity. also, keep in mind my troubleshooting. my ethernet connection disconnected (no IP address), then reconnected (DHCP issues IP address). If there’s a switch between your router and imac, i don see how the router can be triggering ethernet disconnections.’

either way, good luck with your troubleshooting. Apple should be paying us to troubleshoot their products.

Reply

Answer 6

rkaufmann87

Level 10

143,616 points

Jun 30, 2021 4:35 PM in response to xdracco

You may want to provide that as feedback to www.apple.com/feedback

Reply

2021 iMac M1 Ethernet connectivity woes (solution provided)

Similar questions