I have an existing configuration with multiple networks, VLANs and AP configured and working as expected. All the APs are connected to trunk ports on the switch (default, "All" profile). I'm trying to extend the network in the following way, where I need to connect the AP to a port with the non-system VLAN as the native network of the port, through a non managed switch, but doing so results in losing connection to the AP.

More details:

3 VLANs:

VLAN 0 - Management

VLAN 1 - Department 1

VLAN 2 - Department 2

Existing topology:

Router (ER7206) <-> Switch (T1600G-28PS v3.0) <-> AP (EAP225)

• The AP has fixed IP assigned, no DHCP used.
• The network is managed by Omada software controller (5.14)
• VLAN 2 is managed outside the network, such as DHCP pool, network addresses, etc, and connected to via  ER7206 using PPPoE
• Existing clients connect to both VLAN 1 and VLAN 2 through an AP using separate SSIDs/WLANs successfully

Due to physical and cabling constraints I need to extend the network in the following way:

New topology:

Router (ER7206) <-> Switch 1 (T1600G-28PS v3.0) <-> Switch 2 (TL-SG105PE, non-managed) <-> AP (EAP225)

All the hosts plugged physically to the new switch via RJ45 (Switch 2) must be on VLAN 2 (untagged traffic) (requirement 1), while the AP has 2 WLANs/SSIDs for accessing either VLAN 1 or VLAN 2 (requirement 2).

If the port on Switch 1 is configured as trunk ("All" profile as port config), then the AP is accessible and works as expected, and I can connect to both VLANs via the AP, however requirement 1 is not met as the untagged traffic connected to Switch 2 is not going to be assigned to VLAN 2. I thought an easy fix would be to change the native network on the port of Switch 1 so that the native network is VLAN 2 instead of the "default" VLAN 0 (Native: VLAN 2, Tagged: VLAN 0, VLAN 1, Untagged: VLAN 2). When I do the change then AP gets disconnected and I can no longer manage it. 

After lots of troubleshooting it seems to me that whatever I do, if the native lan in the port configuration is not the management lan (VLAN 0), then I lose connection to the AP all the time, and I cannot get the AP working in any other configuration even if I remove switch 2 from the topology, therefore I rule out this is related to the non-managed switch in-between.

I'm looking for a way to configure the switches so that all requirements are met. Is there way to configure the port connected to the AP in a way that the native network is not the management network? Help appreciated.