Was at one of our warehouses this afternoon installing Skype for them so they can call head office for free.

Got Skype installed ok and running but it made their Citrix connection crash and no amount of persuasion would make it come back up.

I tried turning off Skype on the 1 PC it was installed on.
I uninstalled Skype on the 1 PC it was installed on.
I even did a factory reset on their router and reprogammed it all but nothing seemed to work.

It looks like Skype has stolen the port Citrix uses - 1494 - and refuses to release it.

Has anyone else come across this problem before?

Going to try again tomorrow with a spare router programmed from scratch.

Are you saying that installing Skype on one PC prevented the Citrix client from working on any PC on the network?

Did the other PCs work again if you switched off the suspected machine?

I could understand it on just one machine. That could be something simple like a Windows Firewall issue, but on all the machines? Are you sure the server was actually working, and it wasn't all just a coincidence?!

The site has 3 computers all connected wirelessly to their router. All 3 machines were running Citrix Client at the time.

We installed Skype and tested it by calling head office on it - at which point the person on another computer shouted that their Citrix connection had just gone down - on trying to reconnect they got "we could not connect to the server" error message.

The Citrix Server at head office was working fine.

I think the problem revolves around their router and its firewall but I would have thought a factory reset and reprogram would have cured that? Almost as if the router has not released a port properly?

Their connection to browse the web was unaffected on all machines.

The only logical explanation I can think of is that the router at head office locked you out, maybe seeing the Skype call as an intrusion. Is the client on a static IP? I can't think of anything more you can do at the client end!

There's every chance it'll be OK in the morning. If not, a reboot of the head-office router may be called for. Perhaps you could do that tonight?

Both head office and the warehouse have fixed IP address.

I have checked the head office firewall and there is no standing instuction what to do with regards to Skype calls so I have opened a port and told it to redirect any Skype incoming calls on that port to a certain desktop when the head office user sits.

Back at the warehouse tomorrow 1st thing so will take a look at their firewall settings.

We haven't had any problems, we have Skype installed on about a dozen machines and we have 35 Citrix users in remote locations. So far we haven't had any problems, when we do video conferences between the sites.

Firewall and VPN settings? Could it be a bandwidth problem? We get Citrix slowing to a crawl, because users insist on downloading 70MB Excel files from the corporate server to their local machine, instead of looking at it in Citrix...

Ok was at the warehouse this morning and their Citrix was working fine until they had an incoming Skype call from head office - at which point Citrix went down. I tried to ping the server but that failed.

Got back to head office and logged into the firewall and I can see the problem. It was seeing the Skype call as a DOS attack and so had blocked the IP address of the warehouse. I can manually release the block which then got the warehouse Citrix working again however at this moment it means they cannot use Skype between the 2 sites as the firewall will keep mis-identifying it as a DOS attack and block them again

I'm going to flag this with our external IT people as they installed and configured this firewall.

Thanks for your ideas

Can't they just whitelist the IP address of the warehouse?

Yep - just done that.

Got a home-worker who also uses Skype and Citrix so he will try to call us tomorrow to check we have the rule set correctly.