I sure can't see anyone blaming a router that enables diverse items to operate and all except their's. wow.
a new sub with Charter/spectrum came with a hi and low band wy fy and each one uses the same criteria to log on to it. I just chose the 5G expressly for the iMac. everything else runs off the lower band with no issues if within range of course.
OP is right... sometimes its a live and learn thing and learning ain't always a smooth road. hopefully all will settle up soon.
recently I found that by mentioning early on in the emails I was going to post this online in a few forums as to my experience in the matter, that the response came swiftly. in fact one agent called me, shared a screen session and tried to work out the issues himself.
I was getting no traction prior to insinuating going public on the whole of the support affair.
good luck.