down consoles fail to reconnect automatically

Greetings,
I'm running conserver-8.2.1 on an Ubuntu-14.04.2 server, with several
thousand clients, connected over IPMI.  Most of the time it works
fine, however occasionally we lose a VPN concentrator that maintains a
VPN tunnel between remote sites and the console server, and we a large
number of console sessions go into the 'down' state.  Usually when the
tunnel comes back up, the console sessions come back up on their own,
however there are times when they do not come back up for hours, or
not at all for no obvious reason.  In nearly 100% of those cases, if
someone manually runs 'console $consoleName' (where $consoleName is
the name of the console session that is listed as 'down'), it will
immediately come back up.

According to the 'console' man page (
http://www.conserver.com/docs/console.man.html ), if I invoke
'console' with:
-z bringup

it should "Try to connect all consoles marked as down (this is
equivalent to sending the server a SIGUSR1)".  I've tried that:
####
$ console -v -z bringup
console: interface address 127.0.0.1 (lo)
console: interface address 10.200.53.130 (eth0)
127.0.0.1: ok -- bringing up consoles
####

However it doesn't seem to do anything at all.  None of the down
consoles come up ever.  Yet I can still force them up manually if I
connect to them one at a time.

I'm unclear whether I'm misunderstanding how the 'bringup' command is
intended to work, or if there's a bug somewhere.

Can someone comment?

thanks!