TP-Link TD-W8961ND Constant Disconnections

[#1]

Close the unwanted tab/page before you exit Firefox. If that is the only page you have open click the Home icon (which should display your google home page), then close Firefox. Reopen Firefox and hopefully the google page will be the one that displays.

[#2]

HI - worth restarting this thread.
I've had a TP Link TD-W8961ND for a few months, all of a sudden it started doing exactly what the OP reported - in addition my SNR was being reported as "0.-2" that is "zero point minus two"  !
A different router worked fine.
TP Link went through the normal factory reset process, declared it broke and sent a new one - excellent service.  Got it yesterday and the same thing.
So, what is causing this? I'm guessing something changed on my line that these routers don't like.  I have a support ticket in with Plus Net from when it first happened and have just added this thread to my ticket.
Cheers