I use Kerio Control NG300.
I have 3 internet interfaces (LAN 1, LAN 2 and LAN 3 ports) and the "internet" port is connected to an unmanaged switch.
Some PCs connect directly to the switch
Some PCs connect to Ubiquiti acces points that connect to the switch
I have 3 VLANS, for 3 different WI-Fi networks SSIDs. The Ubiquiti software takes care of tagging the traffic from the Wi-Fi side. On the Kerio side I have 3 VLANs configured on the Internet port that do the tagging.
No problem with these 3 VLANs, Kerio and the devices on Wi-Fi can talk to each other.
Now if I create another VLAN on the internet interface, the same way, and I try to contact a PC that is connected directly to the switch (not to Wi-Fi), traffic does not go through.
Making a PC talk on a VLAN is different from joining a wifi that is on a VLAN. The Ubiquiti will tag for you and the PC on the wifi does nothing special.
On a wired NIC you have to set the VLAN in the adaptor settings and it is different from brand to brand so I can't help you there. But it's an idea.
You can try to bypass the switch to see if it's blocking.
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