No, I have no idea what is going on there.
Flash the 386.7_2 firmware onto your main router (if it isn't already installed).
Fully reset the nodes. Do not touch them for 5 minutes. Turn them off. Do not connect to them in any way. Leave them off until you perform the following.
Fully reset your main router. Be sure you are not connected to your ISP (WAN) or any other LAN and/or USB device(s).
After your router is fully reset, perform a temporary setup of the router (just enough to get into the main menu) and fully reset it via the GUI. Be sure you check the box that says 'Initialize all settings...' too.
Perform one more temporary setup and this time, reflash the same 386.7_2 firmware for your model.
Afterward, reset the router again via the Reset Button method, the WPS Button method, and the GUI method.
With the above complete, the nodes still off, the WAN not connected and nothing else plugged into the main router (no WAN, LAN, or USB devices), configure your router with a new User Name (maximum 8 alphanumeric characters), new SSIDs (max 8 characters, no spaces, no punctuation, no special characters, no smiley faces) and passwords (max 16 characters with the same limitations).
Do not change any other settings. Do not even go and look at how the settings are configured in various parts of the GUI. Toggling options and features on and then off is not the same as leaving those same options/features off in the first place.
After letting the router idle for 10 minutes or so, reboot it via the GUI.
Also at this point, reboot the computer you're using to configure it with. Be sure you also reboot any other device before connecting to the router too.
Note that rebooting is different than shutting down, then powering up again. Perform a reboot.
If the issues continue after this point, I would be leaning towards this being a sign of failing hardware.