That log looks like a possible firewalling issue. Can you get on the controller and reach port 4444 on the agent with nc, nmap, or the like? (NB I'm dealing with SSH issues with a Jenkins 2.462.2 controller running on a WS2019 VM and trying to connect a Docker agent running on a Ubuntu 22.04 VM. Node setup is exactly like yours. I can connect but the log keeps showing a rejected key, whether I have RSA, ED25519, or what have you.)