as you are using the HH1 there were post a while ago where people were having problems when ther connection was upgraded to 21CN adsl2 and they were using a HH1. there have been many post sibce where others using the HH1 have not had any problems after upgrade. you could try another router or try CS 08001114567 and see if they will replace the hub.
without a test socket, unable to remove the bellwire and 10 extension sockets there is no much more you can do bar get an engineer id hub does not solve it
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