> I did not have this problem in Debian 10. I do not know if the card's driver has changed between the two versions of Debian, so I am going to boot into a Debian 10 live image and see if it displays the same behavior.
Good news: I verified that this whole thing is indeed introduced in Debian 11 (Bullseye) and is not an issue on Debian 10 (Buster). Bad news: this mean I can't use the card for now! :-) I verified the above claim (bug in Bullseye) by booting into BUSTER using a Debian 10 live USB, and I also tested the same with a Debian 11 (Bullseye) live USB and obviously also with my hard drive install of bullseye. The BUSTER USB booted fine and the interface came up without any issues 100% of the time, several times. I even went back and forth randomly between the different distros, sometimes fully powering off the machine, others simply just rebooting... In contrast, the BULLSEYE USB and the "BULLSEYE hard drive installed OS" each failed 100% of the time and exhibited the same exact problem, every single time I tested them. Another bit of good news (well, progress) is that I also now noticed these logs in /var/log/messages: Feb 22 17:22:53 server1 kernel: [ 1.380198] xhci_hcd 0000:1c:00.0: xHCI Host Controller Feb 22 17:22:53 server1 kernel: [ 1.380205] xhci_hcd 0000:1c:00.0: new USB bus registered, assigned bus number 5 Feb 22 17:22:53 server1 kernel: [ 1.380209] xhci_hcd 0000:1c:00.0: Host supports USB 3.0 SuperSpeed Feb 22 17:22:53 server1 kernel: [ 1.380260] usb usb5: New USB device found, idVendor=1d6b, idProduct=0003, bcdDevice= 5.10 Feb 22 17:22:53 server1 kernel: [ 1.380261] usb usb5: New USB device strings: Mfr=3, Product=2, SerialNumber=1 Feb 22 17:22:53 server1 kernel: [ 1.380263] usb usb5: Product: xHCI Host Controller Feb 22 17:22:53 server1 kernel: [ 1.380264] usb usb5: Manufacturer: Linux 5.10.0-11-amd64 xhci-hcd Feb 22 17:22:53 server1 kernel: [ 1.380265] usb usb5: SerialNumber: 0000:1c:00.0 Feb 22 17:22:53 server1 kernel: [ 1.380396] hub 5-0:1.0: USB hub found Feb 22 17:22:53 server1 kernel: [ 1.380411] hub 5-0:1.0: 4 ports detected Feb 22 17:22:53 server1 kernel: [ 5.508457] ax88179_178a 5-1:1.0 eth0: register 'ax88179_178a' at usb-0000:1c:00.0-1, ASIX AX88179 USB 3.0 Gigabit Ethernet, 00:11:22:33:44:55 Feb 22 17:23:25 server1 kernel: [ 39.576966] xhci_hcd 0000:1c:00.0: WARNING: Host System Error Feb 22 17:26:00 server1 kernel: [ 194.596335] ax88179_178a 5-1:1.0 enx001122334455: Failed to read reg index 0x0002: -22 Feb 22 17:26:00 server1 kernel: [ 194.596338] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x0002: -22 Feb 22 17:26:11 server1 kernel: [ 205.378965] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x0002: -22 Feb 22 17:26:11 server1 kernel: [ 205.378969] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x0002: -22 Feb 22 17:26:11 server1 kernel: [ 205.585506] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x0001: -22 Feb 22 17:26:11 server1 kernel: [ 205.693515] ax88179_178a 5-1:1.0 enx001122334455: Failed to read reg index 0x0001: -22 Feb 22 17:26:11 server1 kernel: [ 205.693524] ax88179_178a 5-1:1.0 enx001122334455: Failed to read reg index 0x0006: -22 Feb 22 17:26:11 server1 kernel: [ 205.693527] ax88179_178a 5-1:1.0 enx001122334455: invalid MAC address, using random Feb 22 17:26:11 server1 kernel: [ 205.693532] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x0006: -22 Feb 22 17:26:11 server1 kernel: [ 205.693535] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x0005: -22 Feb 22 17:26:11 server1 kernel: [ 205.693538] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x0001: -22 Feb 22 17:26:11 server1 kernel: [ 205.693541] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x0001: -22 Feb 22 17:26:11 server1 kernel: [ 205.693544] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x0001: -22 Feb 22 17:26:11 server1 kernel: [ 205.693547] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x0001: -22 Feb 22 17:26:11 server1 kernel: [ 205.693550] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x0002: -22 Feb 22 17:26:11 server1 kernel: [ 205.693553] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x0001: -22 Feb 22 17:26:11 server1 kernel: [ 205.693555] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x0002: -22 Feb 22 17:26:11 server1 kernel: [ 205.693561] ax88179_178a 5-1:1.0 enx001122334455: Failed to read reg index 0x0001: -22 Feb 22 17:26:11 server1 kernel: [ 205.693564] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x0001: -22 Feb 22 17:26:11 server1 kernel: [ 205.693567] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x001f: -22 Feb 22 17:26:11 server1 kernel: [ 205.693570] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x0019: -22 Feb 22 17:26:11 server1 kernel: [ 205.693573] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x001f: -22 Feb 22 17:26:11 server1 kernel: [ 205.693576] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x000d: -22 Feb 22 17:26:11 server1 kernel: [ 205.693579] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x000e: -22 Feb 22 17:26:11 server1 kernel: [ 205.693581] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x000d: -22 Feb 22 17:26:11 server1 kernel: [ 205.693586] ax88179_178a 5-1:1.0 enx001122334455: Failed to read reg index 0x000e: -22 Feb 22 17:26:11 server1 kernel: [ 205.693590] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x000d: -22 Feb 22 17:26:11 server1 kernel: [ 205.693593] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x000e: -22 Feb 22 17:26:11 server1 kernel: [ 205.693595] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x000d: -22 Feb 22 17:26:11 server1 kernel: [ 205.693598] ax88179_178a 5-1:1.0 enx001122334455: Failed to write reg index 0x000e: -22 Feb 22 17:26:11 server1 kernel: [ 205.693604] ax88179_178a 5-1:1.0 enx001122334455: Failed to read reg index 0x0000: -22 And as you can see in those logs there is an issue with xhci_hcd on this card and later the USB ethernet driver complains too and says it's going to randomize the MAC! None of these appear in the logs for the Buster OS Live USB. So, at least now I know why the MAC changes randomly in Bullseye and I also now know that this is a bug that was introduced by Debian Bullseye. Next up: I am going to see if I can install an old kernel onto a bullseye install and see if that makes it go away.
