Ok but my RE is the 830.....

The last two days I cannot connect to the AP with the RE. I can connect with my tablet normally but the RE runs through its setup but is disconnected from the AP according to the menu. Reconnecting...

OK I tried range ext 2 and also lowering the channel spacing 20mhz and trying lowering the Mbps to eg 54 or 130. I do not know the Mbps of the router but it is a recent model zte 931vii vdsl2...

Yes i tried your suggestion before about inputting 11bg mixed instead of 11bgn mixed. This lowers the mhz and bandwidth automatically to 54mbps and 20 mhz but as i said it did not work.

No I don't think it is a captive portal w authentication. I am not sure what u mean but there is no need to do any kind of login to go online once u have a normal connection to the AP much like a...

Nope. Did not work unfortunately. This does not make any sense to me. Could there be some kind of dhcp conflict with the router?