TC appearing with odd name in Airport Utility and dropping out

Hi all,

My setup is Virgin broadband router into which is plugged a 3TB TC with an AirPort Extreme connected using Ethernet run to a different room to extend the wireless network coverage.

All was well initially but I've had Sky Q fitted recently which is also hard wired into the Virgin router; not sure if that's relevant or not.

The problem is that after some intermittent connection problems to the TC it seems to have renamed itself when I look at the network through the Airport Utility. It used to be called Mark's Time Capsule (which it still is if you edit it) but it appears as TimeCapsule-881FA12CBC8A in the Airport Utility screen.

This means my MacBook can no longer find it for backup purposes. Prior to adding the Extreme recently the TC has worked well for years now.

The TC also drops appears to drop out intermittently although the wifi to the Internet still works, it's as if the TC isn't there and the Extreme is connected directly to the Virgin router.

So, the question is, how do I get the name back to what is was so my backups can start again ? Any help as the the intermittent drop outs would also be appreciated.

Thanks in advance.

Mark