Hi,
Currently the path is Asymmetric and hence your ssh session is getting dropped. Your traffic to the VM is over its public IP and you have added a UDR to forward traffic to NVA and when NVA SNATs and sends it back to client, it gets dropped.
You will need to add a UDR rule where if your source is your client public IP next hop as internet and associate that to the VM subnet to which you are trying to ssh.
Regards,
Karthik Srinivas