ex3800 ip address overlap...

My internet router is a Cisco Meraki MX and is set up with DHCP on my local network. The EX3800 receives an ip address and it works.

I've setup both a 2.4 GHz and 5 GHz network on the EX3800 to extend my existing wifi. The SSIDs are named differently than the SSID they are extending.

Whenever I connect my client (which already has an ip address from my existing SSID) to the 2.4 GHz extended SSID for instance, it takes a loong time to hand out an ip address from the DHCP and when finished, it says that there's already a client who has this ip address! 

As a result, I have to reconnect to the extended SSID several times to finally receive an ip address which is not in use - at least according to the EX3800.

The interesting thing is - the ip address it mentions as being in use already - is in fact NOT in use when I look at the Meraki internet router...

Has anybody experienced this? Has anyone a solution?

Thank you.