Satellite has lost sync, can't re-sync

So, I've had the RBK50 for ~8-9 months now, with no major problems. A few hours ago, some issues appeared, where web browsers would give warnings that there was a privacy error. It turns out that devices connected to the satellite (RBS50) were getting the issue, but ones connected to the router (RBR50) would not. Also, unplugging the satellite (which forced all wireless devices to connect directly to the router) resolved the issue. In the process, hard reset modem, router, and satellite.

Upon checking the config page on the router, it shows the satellite isn't connected. So, reboot the router and satellite again. Satellite shows as "config sync" indefinitely. After waiting a while it never changes. Still have no internet connectivity from devices connected via satellite. Try syncing the satellite to the router, using the buttons on both. No luck. Try from the router's config page (hard button on satellite, and button on router config webpage), also no luck. Try having the router generate a new secure password for the backhaul, and then sync again. No luck. Try removing the satellite from the router's config page, so it's as though I'm adding a new satellite, rather than trying to reconnect an existing one. No luck. Try resetting the satellite by using a paper clip, and then syncing it. No luck. Teh satellite now broadcasts the default SSID, rather than the configured one. When attempting to sync from the router's webpage, I have gotten the message "Satellite setup failed" (obviously, I don't get any message when attempting by using the physical sync buttons on both router and satellite, but it does seem to fail then, too).

There are no new devices on the network, and the satellite and router are both in the same positions they've been in for months with no problems. No new obstructions, no new appliances, same ISP and modem (and internet works fine when the satellite isn't on the path, so it shouldn't be related to the ISP anyway). Satellite seems to have lost sync for no apparent reason, and short of resetting the router and reconfiguring from scratch, I've tried everything I can think of to sync it again, with no luck. They both have the current v2.2.1.210 firmware. Modem is provisioned in bridge mode by ISP, and can only route and offer wifi by paying ISP for wifi service, which will result in different provisioning. Router and Satellite are on different floors, plus maybe 50 feet apart, horizontally.

So, in a last, desperate attempt to remedy it before posting this, I had watched a Netgear tech support video on Youtube about syncing them, and in the video, they showed them both on the table next to each other. So I relocated the satellite to where the router is, plugged it in, and then attempted to sync again, and it failed. Router still broadcasting the cnfigured SSID, and satellite broadcasting the default SSID. I tried once more, and it succeeded. Both broadcasting the configured SSID. So then I unplugged the satellite and put it back in its normal location, plugged it in, and waited, and it worked. I then plugged back in the couple devices connected over ethernet. All seems fine now.

At any rate, based on my experience with syncing issues, if anyone else is having issues, I'd try placing them close together and attempting again, and see if that works. My second-to-last resort was going to be attempting to configure a wired backhaul and see if I could get them working that way, and the last resort was going to be factory resetting the router as well.