I'm trying to figure out if I can use one of these Lantiq based VDSL2 modems like the TP-Link TD-W9980 in the U.S.
It's unclear to me if Annex A vs Annex B matters at all for VDSL2.
The firmwares are all labeled as "VDSL2 over ISDN" but I don't think what I have is an ISDN line. I'm on AT&T FTTN resold via Sonic in the SF Bay Area if that tells anyone anything.
Yes, it still does, for VDSL (unlike ADSL) Annex B contains the bandplans for Europe, Annex A those for North America, and Annex C for Japan (not sure what the rest of the world is supposed to use).
It is possible that e.g. a device for the european market with the correct Annex A compatible blob will work in the US, but it is as far as I can tell not guaranteed.
Also as a side note. these lantiq xrx200 modems are often (not always) problematic if combined with Broadcom linecards when vectoring and/or G.INP retransmissions are used.
Thanks a lot! Very good to know. I think I'll steer clear. There aren't any VDSL2 Annex A OpenWRT supported routers out there are there?
Why don't you just get an external modem that's capable of bridge mode? The Draytek Vigor series should be a good match. That way, you have much more flexibility in choosing a router.