Your Premiere can only use the 2.4 GHz wifi band, channels 1 through 11 as are used in North America.
When checking your router settings be sure it is set to use a wifi channel in the range 1 through 11. 2.4 GHz channels higher than this are used in other geographical areas but Rokus don't use them and can't even see them. If your router supports 2.4 GHz channels outside this range make sure your router is set to use a channel in this range and that you aren't using an auto setting that could select channels outside this range.
Roku Community Streaming Expert
I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well.
If this post solves your problem please help others find this answer by clicking "Accept as Solution.".
Streaming Stick 4K+ 3821 | Streaming Stick+ 3810 | TCL Roku TV 43S245/C107X