Move Radius server to Azure

[raz]

Hi,

I'm in the process of moving my radius server used for authenticating VPN clients from my local network to Azure. I've migrated the IAS settings and added the new server in System -> Servers, but when I test the authentication against the server in Azure, I get this error:

"The following input errors were detected:
Authentication failed."

I can authenticate against the local radius server.

Setup:
OPNsense firewall
v. 18.7.10_4-amd64
IP address 172.16.12.2

Radius
Windows Server 2012 R2
IP address 10.100.10.11

I can't ping 10.100.10.11 from the firewall, so it must have something to do with the communication from the local firewall to Azure and maybe a missing firewall rule, but what am I missing in the process? Should I create a new server here VPN: OpenVPN: Servers with another IPv4 Tunnel Network pointing to the 10.100.11.x network? I'm also uncertain if it has something to do with certificates.

There is no problem communicating from my local machine and servers to the network in Azure.

Thanks in advance,
raz