Thank you so much, it helps.

@bullheaded You should try some other non public (public ones may block it) wi-fi network with mobile connection disabled to see if wi-fi calling works with your mobile plan, if you are new to it....

@bullheaded ALG> SIP ALG, Network> UPnP would be in the router management page, like https://192.168.0.1/ or http://tplinkwifi.net/ - not phone. Archer C54 is rather old indeed but should work for...

@MMMcQ BE9300 does negotiate 2.5 G on WAN (internet) port for me. There is nowhere to find it in the router control web page, but you can force port speed instead of auto-negotiate in Network>...

It's just short flat patch cable sold for couple of dollars. Around 5 ft or so. The Cat version should be printed on the cable.

@bullheaded WPS is about using physical button to establish wi-fi connection for the first time. It's not related. You may look for settings like Security> ALG> SIP ALG, or Network> UPnP. T-mobile...