RUTX11 speedtest "Cannot retrieve server list" and can't test Mobile, only WAN

Just chiming in - I see you have IPv6 address assigned to your mobile interface as well, and most applications prefer IPv6 over IPv4. If you don’t have IPv6 on wired wan, I’d suggest changing your PDP type on mobile to IPv4 only to avoid confusion, as even if mobile interface has a higher metric (lower priority), it’s IPv6 prefix will still be preferred over wired wan IPv4