See the main S3DF documentation for detailed information about how to log in, use the SLURM batch system, and so on. Specify --partition roma,milano --account fermi.
Basically, ssh to s3dflogin.slac.stanford.edu and from there ssh to fermi-devl (no .slac.stanford.edu; it is a load balancer, but there is only one node so far) to do actual interactive work. The login nodes are not meant for doing analysis or accessing data. Of course, real computational intensive tasks are meant for the batch system and not the interactive nodes either. Send email to s3df-help at slac.stanford.edu for issues.
You can modify your .ssh config to allow direct passwordless access from your device to ianafermi-devl, by adding this to your .ssh/config file on your end:
Host slac* User <you> Host slacl Hostname s3dflogin.slac.stanford.edu Host slacd Hostname fermi-devl ProxyJump slacl
and then add your e.g.