Netgear D7000 not registering any device on Wifi- please Help

Hi there

I have sort of similar issue. I have got new VDSL2 connection and provider has sent me their own pre-configured modem router (Huawei HG659 ). Previously I was using Netgear D7000 for adsl+2. Since I received this pre config Huawei HG659, I'm using this device as only modem (wifi is switched off ) and have start using my D7000 as router (connected via ethernet cable to WLAN). The day i did this above, I have also updated the firmware of D7000 and since then I'm having lots of trouble with this very unstable wifi connection to all of my devices. surprisingly sometimes only guest wifi work and other times 5ghz. No idea what to do and why this is happening. I have installed advance IP search software on my computer and this software is only showing hard wire connection (which are connected with Huawei HG659), although my computer was connected with D7000 wifi guest connection. Ihave also noticed that when I logged into Huawei HG659 I can see the IP's of all connected devices but non of them getting any internet connection. I have rest the D7000 two times and the problem is same. Since last night I can't even log into D7000 via wifi even though  I was able to log into Huawei HG659 using same D7000 wifi (guest connection).