Apple USB ethernet adapater no longer connects

Thanks for the response.

There are a number of other devices on the same network, all wifi, no issues with any of them. No way to connect any other them with ethernet cable, much too far from the modem.

I switched cables and adapters, no change, same message "Apple USB Ethernet Adapter has a self-assigned IP address and will not be able to connect to the internet."

Turned off wifi and power cycled equipment. No luck.

Firewall not on.

I use this computer infrequently and it's been at least a year, maybe a little longer, since I've accessed internet with the ethernet cable. Same location as now, I was troubleshooting internet issues and Cox asked me to connect directly to the modem to determine if the problem was on their end or something to do with the router. It worked then. What is different now is the OS, currently 11.6.4. I don't recall what it was previously.

I tried my wife's MacBook Air, much newer than mine with only two USB-C ports. She uses an adapter to connect an external USB drive and a monitor. I used that adapter to connect my USB adapter. Same result as with my computer.

I reviewed the article you recommend, didn't see anything obvious. The only other thing I can think of is I have a new Netgear modem since the last time I tried to connect via ethernet. Don't know if there is a setting there that could be the issue. The previous modem when I was able to connect with ethernet was also Netgear. All my attempts to connect now have been through the modem, not the router.

Talked with Netgear who tells me I need to buy a $190 support contract that will cover all my Netgear and Orbi products for 2 years if I want to do anymore than basic tech support. I do have a 4 year replacement contract on the modem with Best Buy but that's replacement only. I think it's a longshot that the problem is a setting in the modem but it could be. Probably an even longer shot that one of their Geek Squad people would know what to look for.

Doesn't it make sense that if this were a defective modem, an ethernet connection to the Orbi router also might not work? I could take the adapters to Apple and have them test but the chance that two of them are bad doesn't seem likely.

Think I'll go have a single mall and ponder all this for awhile.

Thanks for the suggestions.

I should have added, also switched USB ports with both cables and adapters.

As a reminder, I have two identical Apple USB ethernet adapters, both get the same result. "Apple USB Ethernet Adapter has a self-assigned IP address and will not be able to connect to the internet."