Router does NAT, a switch doesn't. So you will not get more than 1 device on internet without NAT as ISP provides only 1 IP address. At this point I lost track what results are you getting connecting...

I'm not sure we are on the same page regarding speed and half/full duplex. There are few options: 2.5G full duplex. 2.5G half duplex. 1G full duplex. 1G half duplex. etc. Half duplex is basically...

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>...