If you are currently powering your Roku device via the TV USB power port, try plugging directly into wall power. If your device did not come with a wall power adapter, try using a cell phone charging adapter (5volt, 1 amp).
If changing to wall power does not help issue, try rebooting all your network equipment (modem, router, and extenders, etc).
Feel free to post update or if you need more help. Include Roku model number from Settings/System/About.
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660x, Premiere+ 3921, Express 4k+ 3941