"authentication via the proxy server was unsuccessful"
I have a Nexus 10 in the UK and am connecting to BT Homehub wifi at home, generally successfully. Quite often, however, I fail to connect and get an "authentication via the proxy server was unsuccessful" message. I've done a pretty extensive search, both here and on the internet and can't find either a reason, nor a solution to this. As most of the time it works, it is more an annoyance than anything else, but I would love to find a fix.
Does anyone have any ideas, please? Thanks in advance...