Restarting your Roku device, and your wireless router/modem is a great first step. Replacing the batteries in your remote can help. Changing the wireless broadcast channel on your wireless router, to one that isn't in use by another nearby wireless network, can reduce wireless interference and be extremely effective in improving remote functionality.
The remotes for my two streaming sticks work fine now. The issue was the internet outage and when the internet came back some settings on my modem had changed. I had to finally call century link about three times to get the issue sorted out.
I had the same problem and no amount of rebooting and taking batteries out and pressing pairing buttons helped! I was able to control the player through the Roku app on my phone but the remote itself would not pair. I have tried all the steps in the support document on this group and watched several other videos of people with the same issue.
I fixed the problem by pressing the hard reset key (almost invisible) on the bottom of the Roku Ultra player and the remote was paired soon afterwards. Strangely enough this procedure is not mentioned anywhere.