On Sun, Oct 19, 2025 at 18:31:38 +0200, [email protected] wrote: > On Sun, Oct 19, 2025 at 06:43:31PM +0300, Henrik Ahlgren wrote: > > From the > > information he has provided to me off-list, it is indeed the case that > > the ethernet-over-USB device in question (essentially a 4G router I > > believe) IS changing MACs on each power cycle, so the names are not > > predictable, without some sort of udev configuration or other tricks.
If this is all true (in which case, WHY didn't he just post that information to the mailing list??), then the obvious solution is to provide configuration which assigns an unchanging name to the interface. systemd.link(5) describes how to do this, but obviously it requires that you provide a way to identify which interface's name you want to change. Normally, one would match the MAC address in order to assign the name, but in this case, that's not an option. So, I would suggest reading that man page and looking at all of the other options, to see which one(s) might be viable here. The PermanentMACAddress= option looks quite interesting. I'm not sure how you would determine whether the device in question has such an address, or what it is. As is often the case, gathering *as much information as you can* and then showing it all to us would be an extremely helpful step. Look at the output of dmesg (or the logged version of same, either in /var/log/kern.log* or in journalctl), and copy *everything* you see that pertains to the network interface. Look for commands that can give additional information about the interface, such as mii-tool or ethtool or dmidecode ... I'm not an expert on this stuff, so a few web searches may give you more tools to try. (You may have to INSTALL some of these tools. Try to use your noggin. If a command that you try gives you "command not found", see whether there's a package of the same name that you can install. Don't make us spoon-feed you every... single... step. You're an adult. Act like one.)
