Razer Sila blocking TP-Link wifi extender

Hi guys, I've been using a Razer Sila for about 3 months now, I've replaced my broadband provider's router by the Sila. (I'm using Virgin Media as a provider) The Sila is connected in my living room (where the old broadband router was originally), everything works great while I'm in my living room, devices connect super fast to the Sila, internet speed is great etc... However my flat has thick brick walls and the wifi signal from the Sila is quite poor at the back of the flat and in my office. It was also the case when I was using the Virgin Media router so I've always been using a TP-Link powerline to create a second wifi signal in my office. And the problem I'm getting is that when I try connecting devices to this extended wifi from the TP-Link powerline the devices can take up to 10min to connect to the wifi and most of the times it just fails to connect. But when I use the Virgin Media router instead of the Sila my decices connect instantly to the extended wifi signal from the TP-Link powerline. It's quite frustrating because I can't just freely walk through the flat and jump from one wifi signal to an other ( Sila wifi to TP-Link wifi ). And it makes thee whole purpose of having the Sila quite unpleasant. So is there actually something in the Razer Sila that is blocking devices that want to connect to a secondary non Sila extended wifi ? Is this just some kind of evil firewall forcing me to only have Raze Silas to create and extend the wifi network ? Many thanks, Nal