Special VLAN Trunk

Hi together,
I have a hAC AP board and run the internet via the sfp1 (comes over untagged vlan 1). Other VLANs are also available via this line (telephony, etc.). Now I would like to continue to have the internet via the SFP1 and forward the vlan 12 untagged to ether5. Unfortunately, I can’t do it no matter what I try.
I loaded the default configuration and added the sfp1 to the WAN interface list, set up a DHCP client for it and removed it from the bridge port (like the ether1 was). So the internet already worked on the SFP1.
But how can I also store vlans additionally there? Unfortunately, most of the instructions only show how to forward vlans or use the internet port only for the internet and set up vlans on the other ports with a default gateway to the internet port, which unfortunately doesn’t help me.
hope someone can help.

suggest your description is mildly confusing.
No need to vlan your internet connection unless the ISP provides the traffic on a vlan.
You bring internet to the router via DHCP Client and normallly use vlans for the LAN side traffic…

Try providing a diagram and the config
/export hide-sensitive file=anynameyouwish

If you want to pass some VLAN to some of LAN ports, then … there many ways to skin the animal. But the most straight-forward way is to go all-VLAN and all interfaces on bridge. Then SFP port won’t be the WAN port, appropriate VLAN interface will be. Look through this tutorial. SFP port will be hybrid port with PVID set for internet.