hi @mugrene , Firstly, happy new year.
I agree with @ww , that 1:1 NAT rule using WAN2 could be causing the issue. Is that external iP coming in via WAN2? If you run a packet capture on WAN1 or WAN2 do you see the requests come in?
Darren O'Connor | uccert.co.uk
https://www.linkedin.com/in/darrenoconnor/
I'm not an employee of Cisco/Meraki. My posts are based on Meraki best practice and what has worked for me in the field.