The stats from your router only show an uptime of 19 hours , so it’s been recently disconnected anyway , using the master socket test port should eliminate any dodgy extension wiring or sockets, so always a useful thing to do , if on digital voice , the 17070 quiet line test won’t assist, but it’s possible your line is impacted by an external issue.
Although the checker won’t work with a DV phone number , it should with your address or UPRN
