My plus.net supplied TG582N router claims that it was updated via TR-069 in February (to version 10. something)
Since then I've had all sorts of bizarre behaviour with my Landfill (android lollipop) cellphone dropping off the WiFi (but still thinking it's connected). This was driving me nuts, as I had assumed it was the usual Android problems, but couldn't fix it or work out what was happening. [debugging supplicant exchanges is non-trivial %-].
Eventually I realised that It wasn't there before the plus.net router remote update, so ...
Switched to an Airport Extreme, and the problem went away entirely; as the extreme has PPPoE support, the TG582 is no longer adding its special behaviour and everything is fine again.
SO ... IF you're seeing odd behaviour with lollipop cellphones & wifi, it may well be an update to the plus.net/technicolor router firmware that's causing the fun, rather than the normal assumption that Android is rubbish.