My network setup managed by an OC200 hardware controller (latest firmware)

I've been strugling with certain IoT devices to connect to my access points. Depening on which AP is use, the devices will or will not connect.

I'm not able to post links so it will be only a description of the device is listed below:

IoT devices:

• Homewizard P1 Meter will NOT connect to my AP653. Connects fine with an AP225.
• Homewizard Energy Socket will NOT connect to my AP653. Connects fine with an AP225.
• Homewizard Water Meter will NOT connect to my AP653. Connects fine with an AP225.
• Vaillant Connect VR940f will NOT connect to my AP225. Connects fine with an AP653.

All devices support 2.4Ghz 11n. The Vaillant devices supports 5GHz also.

Whatever setting I try, those devices refuse to connect to those specific models..

AP and devices have been factory reset without results.

Am I missing a setting? Is there a better way to troubleshoot this? The logs generated have no usefull info if there are logs in the first place..