I am having a similar problem with a Ring 2 doorbell. My rssi is -53. Upload and down load speeds are fine according to the Ring App WiFi test, but connection is still poor. After a lengthy call to Ring I was told my “actual signal strength” is not adequate. They measured the signal using my MAC address. Apparently the self test using the Ring app is not a good indicator of signal strength. Which begs the question “why do they include it with the app?” I have 80 Mbps download and 12 Mbps upload measured at the doorbell but that’s meaningless. I was also told the Ring WiFi extender would not help.
Rings advice: Move the router closer or pay for more WiFi horsepower (I have Xfinity Blast Pro) with the xfinity pods WiFi extender. I asked why can I watch a 4K video at the doorbell on my iPad but still have a signal that’s too weak. The explanation sounded like double talk. Not happy with Ring Doorbell 2 at all!