On-rev server blocked by ISP

[jbv]

Hi list
One of my clients experienced severe problems a week ago
as they couldn't use their client/server LC app and therefore
lost dozens of potential clients.
After blaming the developer for the days and repeating that
the internet connection was ok, the tech support of the isp
finally accepted to do some more research, and finally confessed
that they had blocked the on-rev server, but wouldn't explain
why...
Did anything similar happened to anyone with an on-rev account ?
And is there anything that can be done to prevent any further
problem like that ?
I'm asking the list, because despite sending a couple of urgent
support requests to on-rev at that time, nobody ever got back
to me...

Thanks
jbv