Hi

Looking at the image below for devices plugged in to port 5 will they take an IP address from Lan 1 or 2?

My guess would be neither because judging from screenshot you have port based vlan which won't work with 2 subnets on 1 port:

Note: Once VLAN configuration is enabled, every LAN port should belongs to one VLAN.

https://www.draytek.com/en/faq/faq-connectivity/connectivity.lan/how-to-setup-multi-subnet-with-port-based-vlan/

Up until 5 minutes ago, I had the same (mis)configuration (on a 2860n) :oops:

It appears that when an existing device asks for a DHCP renewal, it's honoured. Otherwise, if you plug a new device in, I'm guessing it will be luck of the draw, which LAN the IP address is issued for...

...though, just to add - in my case the device in question had a Bind-to-IP address entry.

I have a wireless guest SSID set up to use LAN2, with two AP902s connected by cable from a switch which is in turn connected to LAN port 1 on the 2925. The switches in the AP902s and the switch itself are used for wired connections on LAN1. So in the VLAN setup I have both LAN1 and LAN2 ticked for port 1, as otherwise I could not see how the Guest network could work from the AP902s. Two other SSIDs on the AP902s use LAN1 addresses.
I have tagged the guest network.
Any wired clients on the switch and the AP902s get IP addresses from LAN1, only a wireless client connecting to the Guest SSID gets an IP address from LAN2.