What you describe typically points to a couple possibilities. Wifi signal interference or low transformer power or remotely improperly installed chime controller if you are using chime controller.
How far is the router from the doorbell and how many walls or floors does the wifi signal have to travel through to reach the it? Have you tried moving the router closer to the doorbell (realizing it’s easier said than done)?
What is the voltage rating of the transformer? Front and rear doorbells? Do you have a multimeter and can measure voltage at the doorbell?
This conversation may be beneficial to you;
https://forums.wyze.com/t/video-doorbell-v2-unstable-signal/3422055