And it's the usual 'reboot the router'.
So after experiencing the problem multiple times I have found that the issue is always is on the PC/Media server side. (I am using Windows Media Player as my streaming server). Although it looks like the media server is running, disabling and re-enabling the server fixes the issue each time. Shortly afterwards my media server appears on my Roku (and other devices) as an available streaming server.
Welcome and thank you for posting here in the Roku Community, @LarryD.
We sincerely apologize for any trouble and inconvenience this may have caused you. Rest assured that we will find you the best resolution possible.
May we first know what you are using the Roku Media player for? Is it to view your photos, videos, mp4, etc.? Also, we can try to reboot your router or might as well connect your TV to an alternative network such as a mobile hotspot to see if it will make any difference.
Let us know how it goes; we'd be happy to continue assisting you with this. We'll be anticipating your response!
Best regards,
Carly