EX7700 Extender - login failures

Using the EX7700 with all lateset firmware. This is connected to my D7800 VDSL Modem router.

Using my desktop which is wired to the D7800 I try to login to my extender (EX7700) using Firefox and mywifiext wgicg usually works fine. But I have had problems with this since I have had the extender. Several times now I have used this and just been left with a blank screen. My D7800 is connected to it (router attached devices page). The only way I can resolve this is to use the IP address which then gives me the login page which comes up as New Extender Setup!. The solution I find is just to power the extender OFF for a while and then power back ON. The extender then works fine.

I have had to do this at least 10 times since I have had this extender and it is still within its 2 year warranty.

NOT GOOD. I would have expected this to be more stable than this over a 2 year period!

Any help/resolution/others experiencing this issue?

No point going back to NETGEAR themselves as they will not talk unless you pay them more money!

Already done this for a long chat and to be given the instructions for resetting!