EX7700 Nighthawk Extender IP Address issues

So, I'm having some issues with getting my EX7700 extender to work properly with my WiFi router.

I can set up the extender and access the extender monitoring page through the 10.1.x.x IP address, but every 12 hours, the WiFi devices that are connected to the extender drop connection for a while (I believe 4 hours or something like that). DHCP lease time is set to 24 hours in the router.

I can get the connection to return to the devices by manually going into the router and releasing the IP, but this is surely something that should be happening automatically.

Also, the concerning thing is that when this issue happens every 12 hours, I cant even just connect to the main router as I'm prompted with the same WiFi IP conflict message on my macbook or exclamation mark on my iPhone. When I go into my network settings on my mac, it says that the IP 168.194.254.x has been assigned to it which is conflicting (and also is the wrong IP as all the IPs on the network are 10.x.x.x.

> Is this a DHCP error? I would set the lease time to unlimited, but I don't want to mess about with the router too much as it is my landlord's next door (they are aware and happy for us using their internet).

> I did originally set up the extender to work with one-name wifi SSID and then manually reset it and set it up to work with different SSID (Wifiname_EXT) - I was wondering if the router originally being set up with one-name messed up the settings.

> I was booted out of the setup of the extender when it came to connecting my WiFi devices - is this the culprit? The extender was clearly working when I could see the ethernet was working and I could connect my wifi devices afterwards, but I'm now thinking being booted out of the setup may have caused an issue.

> The extender is connected to my laptop through one of the ethernet ports and never drops internet unless I unplug it from the extender (weird).

I'm desperate to fix this, so I'd appreciate any help and troubleshooting.