To save money, I would have just switched to ATT fiber like you did, drop Xfinity completely, and try that for awhile. It's worked for me for years, and my only downtime has been a few times during winter storms when the power goes out completely.
> 1. Downgraded Xfinity from $90/mo to a basic $50/mo plan (still usable speeds, just lower tier)
> 2. Added AT&T Fiber as a second line at $55/mo (different infrastructure = different failure modes)
> 3. Bonded both connections using WireGuard VPN and OpenWRT routing
Edit:
Another lie detected: ATT isn't accepting new customers on DSL, and is in fact yanking service for existing customers in many areas. So there's zero chance that OP signed up for ATT copper internet within the last year or so.