RBR50/RBS50 system slows every morning

Yesterday I went back into ("de-bridged") the Xfinity gateway, confirmed the WiFi radios were off, then set bridge mode again and did a full reset on the AC3000, router and sat. "Rebuilt" the network from scratch. Once up and running it was blazing along at 557mbps at my desk. Perfect.

This morning ... first after confirming with the phone app that my iMac is properly synced to the sat just 15 ft from my desk ... 42mbps. Ugh. Checked with a network scan and I'm getting a signal of -39 on 5GHz at my iMac. No interference from any other users (mine is the only system using channels 1 and 48). Couldn't be better. The Orbi is synced and working perfectly except ... it seems to go to SLEEP every night and performance drops by a factor of more than 10 without a reboot. 

I realize this is an aging Orbi but I had similar issues that took at least a month of debugging (ridiculous) when I bought it years ago. This should be a very simple and straightforward setup. At this point I am ready to trash it and buy something else. Another brand.