Hi Daniel,
Your error message is normally because the ESXi servers/EAM/vCenter cannot reach the URL.
From your PC try to browser to http://192.168.100.x/PA-VM-NSX-7.1.0.ovf.
If you can successfully download the OVF, try from the ESXi server.
Check the EAM log to see what is the error.
From your last screenshot, click Resolve and take a note of the time.
Then go to your vCenter and look for EAM logs on the time NSX failed to deploy PA OVF.
If it's a vCenter Server Appliance, try below commands
cat /var/log/vmware/eam/eam.log | grep "URL"
or
cat /var/log/vmware/eam/eam.log | grep "Validating URL"
Also verify your NTP & DNS settings make sure all components time are sync and resolvable from DNS (forward & reverse)