The SSH function on router can only server for Tether 2.0, and does not support SSH clients to login.

Try ping the router's LAN IP on your computer, and see if it's normal. Then ping the Internet gateway IP of the router. Will the high ping affect your internet usage.

Do you mean if your TV and phone are connected to different Wi-Fi band of the router, then you cannot see the cast button on your phone?

It's normal USB transfer speed on a router is slower than on a computer, for the router, I think the speed is ok.

Is your router EU or US version? What's the current firmware version? Did you try it on Android phone?

If your printer is connected to the router's USB port, and printer is not in the compatible list, then they may not compatible. If your printer is connected to the router via Ethernet Cable or Wi-Fi,...