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WiFi Clients connected to same AP can’t connect to each other

I have a UniFi DreamMachine Pro in my home network.

One access point is connected to it directly via a ethernet cable.

Also I have split networks (VLANs) for my home devices, guests, IoT etc.

I currently have the issue that my HomeAssistant (Raspberry Pi, connected via WiFi) from time to time can’t connect to other devices (Wireless) in the same VLAN when they are connected to the same AP.

I can ping the devices from the same AP on another device, while being in a different VLAN. I have also already tried to disable Client Device Isolation on the Wi-Fi network but unfortunately that didn’t help.

Do you know how I can fix this issue so that the devices can communicate?