Contact sensor keeps going offline state unknown

I have ring alarm system and 3 contact sensors. The 1 on my back door keeps disconnecting and saying status unknown. No mention of battery level getting low or anything in event history. Never reconnects unless replace batteries. When I replace the battery it does come back online. I’ve replaced the batteries 4 or 5 times but each time it happens after few weeks. It hadn’t happened for the 2-3 years prior to recently. I’ve just factory reset it and changed batteries again but wondering if anything else that need to do or any thoughts on what may be causing the issue please