On Machine A, I start Remmina (0.8.0) and created a VNC Incoming Connection profile. port 5900 was chosedn, with a username and password. No changes under advanced or SSH. I start the profile and it says "Listening on port 5900 for an incoming VNCI connection..."

On Machine B, I start Remmina and create a VNC profile. I set machineA.local:5900 as the server, enter the username and password and leave everything else as-is. I start the profile and it says "Connecting to 'username@machineA'..."

However this does not connect.

So far I've:

Made sure UFW isn't enabled
Confirmed I can ping and ssh from Machine A to Machine B and vice versa
Tried on other ports
Tried without a username and password
Enable the port 5900 and Machine A IP address on the network firewall

Diagram of setup:

Machine B ubuntu (VNC profile) --->Firewall----> Machine B ubuntu (VNC Incoming connection)

I want to establish an RDP session with another Ubuntu machine but Terminal server client fails with a black session screen and X11VNC fails with too.

Running out of alternatives, has anyone setup an RDP/VNC connection successfully between 2 linux machines and if so how?

Thanks in advance.

Solved it. Very simple issue with the client itself.

Using TSclient oR KRDC, (use RDP) in the connection settings do not enter any username or password as XRDP will
prompt you for these in the remote desktop screen which appears.

XRDP must have conflicted with the attempted login before the console windows opened.