Orbi RBR863 reboots, connection drops after recent firmware releases

The only firmware versions that work with my Orbi are V7.2.6.31_5.0.24 and previous versions. The latest firmware versions result in slow download speeds, random dropouts/disconnects, and reboots. I have tried updating one by one manually, then a pinhole reset, with the same results. However, version V7.2.6.31_5.0.24 is starting to show issues across my network, such as device disconnects and random restarts. I am wondering if anyone else is having these issues and, if so, how to fix them. The units I have are engineering samples; I have had them since before the 860s were released.