Ring Devices requesting multiple IPs

I have 8 devices (currently on their own SSID tunnel on my home network that is Fortigate, Fortiswitch ad Fortiap) 6 that use 2.4G and 2 that can use and seem to prefer 5G. Last week they have begun requesting multiple IPs which has caused them to be "Removed due to IP conflict". 8 devices have filled up the whole DHCP table which at one point showed over 300 devices. This has been set up for almost 2 years and has run without issues. Current lease time on the gate is roughly a week which hasn't been a problem. I shortened the lease time to just over a day as apparently Ring devices can request a new lease every 12 hours and I cleared the table and factory reset one of the devices to attempt to reconnect but it will not connect even though the number of devices showing in the table was under 10. Has my gate somehow "blacklisted" the MAC of those devices? Ring cameras and the base station which are hard wired are working fine, this is a wifi issue. Is it best to try to avoid IoT wifi devices particularly those which rely on 2.4G?

I'm waiting for a service package for the ap to be processed but in the meantime is there anything I can try? I have a neighbour who likes to sabotage my security efforts and wondered if he was somehow able to deauth the wifi devices. It's also possible that the Ring devices have some kind of glitch although there are 3 different models so it seems unlikely that it is some kind of software bug due to an update etc.