Wired doorbell pro/plus - disconnects from Wifi

Good morning everyone, I have been chasing a ghost for a few days now. In short, the doorbell continuously disconnects from wifi.  long story: Firstly, helping my grandma with installing the ring for her. She had one previously installed 2018 worked perfect. One day it stops showing live feed and capturing video. She thought the time was over and wanted a new one. The new one comes in (wired doorbell plus/pro) I install it. Setup went well everything worked. I go to show her the features. Stops working. I got it to connect again with a simple reboot. Next day it stops working again. I go there and try to get it to connect. But it doesn’t whatsoever. Got on a call with a ring tech, he stated I did every troubleshooting step possible. The tech follows up with saying since it’s a week old return it and get another, it appears to be defective. I do so. I know the connection is horrible, RSSI in the high 60s, low 70s. I also got the chime pro as a booster to help. The router is downstairs far away. They have fiber there and I wanted to take an easier approach before running wire and moving the router. new chime pro (2nd gen) and ring doorbell (same model) come in. I get the doorbell setup perfectly. Was having trouble getting the chime pro to connect to the ring, after doing a reset (orange button) it went into setup to connect to the doorbell. Everything works, the RSSI is now low 40 and high 30s. I go to show her the features. Stops working. App shows the doorbell is offline and the chime pro is still online. I simply unplug router and turn it back on. The doorbell after 10 minutes starts working again. Next morning get a text saying it’s back offline. But the chime pro stays online.  I am stumped. I have tried everything possible. There is good connection now from the chime pro network (RSSI 37-48), there is good voltage (15-16v).  Why is the doorbell constantly offline? What can I do? I have tried everything possible from my knowledge, other than moving the router. They have fios. ONT and router was installed a year ago and ring was working fine then. Again want to state that the chime pro never loses connection and goes offline, but somehow, the ring does.   my next step was running wire and moving router upstairs. Otherwise I was going to test the ring at my house to see what occurs. What else can I do? Thanks for the help and my apologies for the long story. I wanted as much info listed as possible.  Ring equipment chime pro 2nd gen wired ring doorbell plus/pro ONT and fios router (unsure of router model)