Kicking hung imaps connection

Running wanderlust on a Mac (macOS High Sierra 10.13.6), but my issue
is surely generic.

There are times when the immaps connection that WL uses hangs, and I
know its not coming back. So I want to nuke the existing connection
and open a new one without waiting for the normal timeout.

Is there an easy way to do this? Ideally, I'd bind some emacs code to
a key to do this.

Example, I'm on a random site's visitor network. It uses NAT to get to
outside world, and NAT bindings are apparently reclaimed after short
period of idleness.  If my connection has been idle for (say) 10
minutes, and then I go to look at stuff, the imap connection hangs.

tcpdump show me retransmitting, but getting nothing back. Eventually
(after a minute or two) new connection starts on its own.

I want to do be able to avoid the wait.

Another common use case is if my VPN disconnects and reconnects, or if
I resume from sleep and have a new local address.

Thanks!

Thomas