Tried to set up 8x EAP653's with my OC200 today, ran into issues because they either did not adopt, or if they did adopt would soon disconnect.
Worked out the issue was them falling back to their default IP 192.168.0.254 during the adoption process, despite having one assigned on the correct subnet by the router.
NB my subnet is not the same as the default fallback one 192.168.0.x so I think that got it confused as it could not reach them anymore mid adoption.
Had to log into each one set a static IP and then adopt, this worked. 

However, its a massive inconvenience as you need to reset them, change password, set up a network, then adopt them, I am just glad I did not install them before I found the issue as they need a hard reset to get them out of adopted mode when the adoption finally fails.

I suspect the fallback IP code has some issues and it chooses to fall back despite having been issued a valid DHCP IP.
Did contact tech support and they seem to agree its an issue and said they'd raise it with the dev team.

Posting this here to help other avoid a whole day of frustration.