I need to set custom DNS to an SSID that is in NAT mode. The reason is that we have a visitor that needs access to his internal system through VPN.
I just followed this guide: https://documentation.meraki.com/MR/Client_Addressing_and_Bridging/Configuring_Custom_DNS_for_an_SSI...
But on his computer i still don't get the custom DNS i just sat.
What am I doing wrong?
You will not see the custom DNS servers you set on the client. The client will always see the AP as its DNS server. See this note from the article you linked to: Note: Wireless clients will still use the AP as their DNS server, this configuration customizes the destination server of the AP's DNS proxy.
How about that visitor changes his DNS on his network adapter? its clunky and not as elegant as the wifi doing it but it should get the job done.