Cloud-init fails / Networking - DNS Problem?

Hello, I am new to MaaS.
My Setup:
I got 3 Proxmox Servers (in a Cluster), on one of them there is MaaS 3.2.5 (via Snap) on Ubuntu 22.04.
Multiple VLANs important are 2, DMZ (MaaS and future VMs are in here) and Management (Proxmox and Switches).
Also there is an OPNSense Hardware Firewall which acts as DNS, DHCP, Gateway.
I installed MaaS, set DNS (on the configuration page) to Cloudflare.
DHCP on the DMZ VLAN has MaaS as network boot and DNS as Cloudflare.
(Picture 1+2)

This is the MaaS Subnet config
(Picture 3)

When I create a new VM in the DMZ VLAN it does find MaaS, starts to boot from it.
That’s the “last” screen
(Picture 4)

I noticed that one step when the pre linux boots (or installs?) takes long
(Picture 5)
Also i can see for like a second that a mirror cant be reached.

I would assume some DNS Problem or so, thing is the same VM booted from a ISO does work just fine, has a connection etc.

I also tried MaaS 3.1, setting DNS to MaaS (and enabled Allow DNS resolution) as well as setting the DNS to my OPNSense.

Does anyone have an idea what my problem could be or how i could troubleshoot further?

Here are some Pictures and Logs: