@Jules987
In addition to @Strega suggestion, if you have a RokuTV or ethernet-capable Roku device, should also be able to used the Wired connection (ethernet) to get around this issue.
After you connect with your mobile app remote , should be able to go to Network Settings and connect the RokuTV or Roku device to your new wireless (wifi) network.
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660, Premiere+ 3921, Express 4k+ 3941, Streambar 9102