Cannot install OPNSense or pfSense - "Could not read from CDROM (Code 0004)"

[xrayxrayxray4098]

Noob here, trying to install either pfSense or OPNSense on Proxmox VE 7.2-3.

I can install other VMs (e.g. Ubuntu, Alpine) with no problem.

However, no matter what I try with pfSense or OPNSense (I have tried ISOs from both), I keep getting the same message when I start the machine, meaning I can't install it:

https://imgur.com/a/uk8Mcam

Here's my current settings for the VM, which I have tried changing multiple times.

https://imgur.com/a/IqUwQI6

Will post details of my machine in next comment, as I can only add two pieces of media here.

Any suggestions?

 

[xrayxrayxray4098]

And here are the details on my host machine, which is an AX41 hosted by Hetzner:

https://imgur.com/a/CO0pO26