HP ProCurve switch VLAN - passing through a VLAN

SysAdmin here trying to configure simple VLAN on HP ProCurve and getting confused with trunk/tagged/untagged VLAN terminology between different brands. Wan't to make sure I got this down correctly.

Here is how the hardware is connected:

Ubiquity UAP -- [port 11] --> HP ProCurve 2530 -- [port 1]-> [port 1] HP ProCurve 1810G -- [port 2]> Fortigate

Purpose: Have the AP segregate Guest from internal network via VLANs (i.e. the UAP slaps on a VLAN tag on the guest SSID connected clients, which then only goes to the Fortigate).

I have setup the AP - tagging the guest network with VLAN 253. The Fortigate has a virtual network with VLAN 253 handing out DHCP and NATing to the Internet. Now I just have the HP switches to configure as seemingly they do not just pass-through VLAN tags by default.

So to make sure I understand: to pass-through VLAN 253 I need to set it to "tagged" on all ports it will pass, leaving the default VLAN 1 in an unatgged state to allow normal traffic without a VLAN (i.e. endpoints don't know about any VLAN) to pass through.

Some people have test network, other have an extra production one ;).

Now I just need to find out what the IP of the 1810G switch is... maybe some lldp with help.

Thanks to all in advance.