Add a new interface. In the device field scroll to the bottom of the drop down list and type eth0.1 , confirm with Enter. Protocol can be static or dhcp client for the admin interface, the rest better be unmanaged.
Then create an new SSID and add it to the network you created earlier.
Do not try to use tagged and untagged on the cable. All VLANs should be tagged.
You'll want to create an "admin" network with a wifi AP and a DHCP server so you can always log into the AP over wifi whether the Ethernet is working or not. This network doesn't need a firewall zone since the default firewall accepts input on unassigned interfaces. It also doesn't need to forward to the Internet since it is for local control.
A link from a main router over a VLAN to a dumb AP involves a software bridge from the wifi to wired. First use the Devices tab on Network-Interfaces to create a bridge for each VLAN. Name them something consistent with what they do such as br-vlan2. The only device yet in that bridge will be eth0.2, as @trendy said you need to manually create it at the bottom of the list. Then create a matching network called vlan2 with protocol Unmanaged and br-vlan2 as its device. This network doesn't do anything since it has no IP address, but it has to exist or the bridge won't actually be created. Then create a wifi AP with vlan2 as its network.
Im going to give this a crack tomorrow. I actually had it working but I thought it was messy, now im starting to think it wasnt messy as I thought I could do away with the bridge interfaces.
I need to tag everything as its a trunk on the other end.
2 of the 3 vlans will have wifi SSIDs.
Do I need to create bridges if im not using wifi and only using ethernet? Because im pretty sure I tried that but could not see any TX/RX interface on 2 of the 3 VLANs, only one. Its like they would not negotiate or were not accepted in the trunk for some reason.
No. You can create an interface and directly use an eth port (with or without VLAN) as the network's only physical device. The kernel will place an IP address directly on the port instead of on a bridge.
The switch configuration, including the trunk ports
The OpenWrt AP configuration
Have you verified that your router and switch are configured such that you can reliably connect to each network? (If not, I recommend setting one port per network on the switch as an access port and then connecting a regular computer to each port in turn to verify the network functionality.)
Earlier, I suggested that you share your OpenWrt configuration so that we understand what you've done so far and find any misconfigured bits. Would you be able to post it?
I agree with @mk24 that you should upgrade to 22.03.2 and that the conic contains stuff that should not be here (specifically, bridge empty and the MAC address overrides). I'd go further and suggest that you don't need to define the device, only the bridge...
So, looking at the above, it should all simplify to this (and this should be used as an example for the rest of them):
option type 'bridge'
option name 'br-vlan103'
list ports 'eth0.103'
option ipv6 '0'
Next, the wlan devices should not be defined here... these are unique to the wireless config file, they do not belong in the network config.
Then, lookin at VLAN 101... if this is not your management network, it should be proto none (just like VLAN 102).
Finally, for VLAN 103 (which you stated is your management VLAN), check to make sure that the address is not used anywhere else on your network, and make sure the netmask is correct (if you are using a /24, this should be 255.255.255.0; what you have corresponds to a /28 with a maximum of 14 hosts). Further, if you want the OpenWrt AP to be able to reach other networks (or the internet, including the OpenWrt repos), it needs a gateway and DNS defined. So verify that your VLAN103 is correct for your upstream network.
It is also worth noting that you did not post your wireless config, so we don't know if you have properly connected your networks to your SSIDs.