Orbi RBR40 devices having trouble between router and antenna

A while ago we purchased an orbi router antenna combo. We purchased it to run WiFi connection across two apartments and approximately 2,100 sq feet ( and we kept in mind that the 5 ghz would have trouble through the exterior walls). We had some issues at the start that were resolved by an RMA. however, now the issue we experience is when going from one apartment to another. When a device is connected to the internet through the antenna in apartment 2 (a2), if they go over to A1 and connect to the router, all of a sudden their internet doesn’t work. When trying to troubleshoot on the router, it usually claims that the antenna is disconnected, which could not possibly be true as a2 still has a plenty strong internet connection. I’m trying to avoid a factory reset as that causes a lot of issues and set up of smart device across both apartments. Also, I haven’t had much of a chance to really test outright speeds, but devices going from a1 to a2 seem to experience the same phenomenon.