For my Stickup cam I have exactly the same setup: battery and solar panel. If you read my previous postings, my last issue has been on April 24th, since the it’s been working perfectly. What I see in your post is that your RSSI swings from -40 to -55, that’s quite a spread. You could have interferance in your channel. My RSSI holds steady at -33 to -34. day and night. In my neighborhood I have a lot of 2.4 and 5.0 GHz users so I look and see what channels are available on 2.4 GHz with the least or no usage and that’s what i select. Ring has published a chart for the cams and I set up my routers and accordingly. Everything works fine.
In that chart see Compatible Networks, make sure you’re at 2.4 GHz. Some have tried to set up their cams at 5 GHz. I did too in the beginning, did not work too well.