Scenario: using SSHFS mounts from my laptop to a central server, the SSHFS mount is broken after a longer disconnect (e.g. during suspend), cause the underlying SSH connection timed out.

Use -o reconnect,ServerAliveInterval=15,ServerAliveCountMax=3

The combination ServerAliveInterval=15,ServerAliveCountMax=3 causes the I/O errors to pop out after one minute of network outage. This is important but largely undocumented. If ServerAliveInterval option is left at default (so without the alive check), processes which experience I/O hang seem to sleep indefinitely, even after the sshfs gets reconnected. I regard this a useless behaviour.

In other words what happens on -o reconnect without assigning ServerAliveInterval is that any I/O will either succeed, or hang the application indefinitely if the ssh reconnects underneath. A typical application becomes entirely hung as a result. If you'd wish to allow I/O to return an error and resume the application, you need ServerAliveInterval=1 or greater.

The ServerAliveCountMax=3 is the default anyway, but I like to specify it for readability.

fstab entry example for laptop, automount after network available:

nuc:/   /media/kodi     fuse.sshfs      reconnect,ServerAliveInterval=15,ServerAliveCountMax=3,auto,users,_netdev,x-systemd.after=network-online.target    0       0