No the changes for “net.ifnames=0 biosdevname=0” were still in there. Those worked fine for debian 8, 9, and 10 (with adjustments made in udev rules to rename eth4 and eth5 to wan0 and wan1), but neither option seemed to have any effect after upgrading to deb11. When I went searching for renaming the devices in deb11, the first several articles all stated to create link files in interfaces.d, but after all the trouble I went looking further and finally found one that referenced putting the link files in the systemd folder. I just linked the files so they are available in both locations, and that change has continued working for several further reboots so I’m crossing my fingers.