Teste ssh -vvv <host>
para depurar problemas.
Isso deve funcionar:
Host myalias
HostName fully.qualified.domain.name
Host fully.qualified.domain.name
Port 2222
LocalForward 3690 127.0.0.1:3690
Editar:
Para diferentes opções, use diferentes aliases.
Host alias1
HostName fully.qualified.domain.name
Host alias2
HostName fully.qualified.domain.name
LocalForward 3690 127.0.0.1:3690
Host fully.qualified.domain.name
Port 2222