Forward VLAN from Unifi Switch through Netgear to Unifi USG

Hi Community!

I have the following simple network setup:

[Unifi USG] -- Port1 -------- Port24 --> [Netgear JGS524PE] -- Port23 ---- Port8 ---> [Unifi 8-Port Switch] -----> [Unifi WAP]

• The Unifi USG is the Gateway and connected via Port1 to the Netgear Switch Port 24
• The Netgear Switch is connected via Port 23 to a Unifi 8 Port Switch
• The Unifi 8 Port Switch is connected to a Unifi WAP

This setup works fine, as long as the WAP just has one SSID and there aren't any VLANs.

With Unifi I can configure the WAP to broadcast two SSIDs:

• Office (Default VLAN1)
• Guest (VLAN8)

The Netgear switch should just forward the VLAN8 packages from the Unifi Switch to the Unifi USG, i.e., forward VLAN8 between Port24 and Port 23.

If I just use the factory settings of the Netgear Switch, it doesn't forward the VLAN8 traffic.

Note, I'm not an expert with VLANs!

So what I tried to do on the Netgear side (see also attached Screenshots):

1. Enable Advanced 802.1Q VLAN Configuration
2. Add VLAN 8 
3. Set VLAN1 Membership Port1-Port22=U, Port23=T, Port24=T
4. Set VLAN8 Membership Port1-Port22=Not selected, Port23=T, Port24=T
5. PVID settings are by default all set to 1
6. Check Membership of VLAN8

As soon as I apply these settings, the devices on the Ports 1 to 22 can not access the USG on Port24. Also the VLAN8 is not forwarded. Only after I set VLAN1 on Port24 to U, at least the Office Lan works again.

Am I missing something in this setup?

Thanks for your help!