Ive been running Ultra VNC SC version for about 2 years without any issues, listening on port 5501 and having our external staff instigate connection to my pc as and when needed.
This has worked very well up until about a week ago.
Suddenly, I can get no one to connect, I always get a message on my machine ( the listening viewer)....
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Connection Failed - Error reading Protocol Version
Possible causes:
-You've forgotten to select a DSMPlugin and the server uses a DSMPlugin.
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OK, I have never used a DSM Plugin and dont wish to. Ive not changed the software untill yesterday when I downloaded the new veiwer, but still has same error message.
Any Ideas as its driving me mad

One thing to note is that I am on a corporate network, ports are open on the router/firewall and have not been changed, however an up to date version of Trend Micro Server Security Virus software has been installed!
Could this have something to do with it? Can it block ports, Im not aware it does but am unsure.
Any help would be happily received.
Thanks