I've set up the hardware as per the above topology and installed the Omada software controller on my Synology NAS. I  can see the ER707-M2 in the Omada controller, which I have adopted. I've run into 3 issues, which may or may not be connected:

1. I cannot connect to the default SSID of either of the EAP650s. I can see the default SSID in my phone's WIFI section but it gets stuck while connecting.
2. There is no internet access for my Desktop PC.
3. I cannot see any of the other devices (ie. the TL-SG105-M2 switch or the APs) in the Omada controller, I only see the ER707-M2.

I've tried to update the firmware of the ER707-M2 (downloaded from https://community.tp-link.com/en/business/forum/topic/718232) but I received an error message on the Omada controller:

I've also tried resetting the ER707-M2 to factory settings, rebooting all of the hardware, etc. But nothing works.

Any help is most appreciated.