usb-ethernet not negotiating link automatically

Kevin

8/25/24, 9:51 PM

Device in question: lsusb tells me ID 0bda:8153 Realtek Semiconductor Corp. RTL8153 Gigabit Ethernet Adapter This is a Monoprice branded USB-A 3 adapter.

Running Ubuntu 20.04.6 LTS

In network manager, the connection says Speed: 1 GB/s

When I plug this USB-Ethernet device into a gig switch, that works fine.

But I frequently plug into devices that only support 100 Mbit. When I do, I get:

# mii-tool enx00e04c680835
enx00e04c680835: 10 Mbit, full duplex, no link

If I force it, it will eventually get a dhcp address and stay on the network at 100 Mbit, but if I only run mii-tool --force=100baseTx-FD enx00e04c680835 once, it'll momentarily say enx00e04c680835: 100 Mbit, full duplex, no link but then revert to 10...no link

Sometimes I get lucky and it'll work first time, but usually it takes several tries before it flips to "link ok". i.e. if I run mii-tool every second:

enx00e04c680835: 10 Mbit, full duplex, no link
enx00e04c680835: 10 Mbit, full duplex, no link
enx00e04c680835: 100 Mbit, full duplex, no link
enx00e04c680835: 100 Mbit, full duplex, no link
enx00e04c680835: 100 Mbit, full duplex, no link
enx00e04c680835: 10 Mbit, full duplex, no link
enx00e04c680835: 10 Mbit, full duplex, no link
enx00e04c680835: 10 Mbit, full duplex, no link
enx00e04c680835: 100 Mbit, full duplex, no link
enx00e04c680835: 100 Mbit, full duplex, no link
enx00e04c680835: 100 Mbit, full duplex, link ok
enx00e04c680835: 100 Mbit, full duplex, link ok

Repeatability: I have two of these dongles, and the bad behaviour is consistent across both of them, so it's a software issue, not a hardware one. I also tried an Apple-branded USB-A to 100 Mbit dongle, and that works. I also tried a "USB-A 3 hub with ethernet" from Monoprice, and that works without need for mii-tool either.

This started happening a few months ago; it used to work just fine. Did something change in the driver? in Network Manager? I'm stumped what is messing with my device.

0 + 1

usb

ethernet

chili555

8/25/24, 11:52 PM

Please edit your question to add the result of: `lsmod | grep r815` and: `sudo dmesg | grep r815`

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EN: usb-ethernet not negotiating link automatically

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