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VNC connects via VPN and LAN but only BLACK SCREEN via WAN

Posted on 2006-07-23
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Last Modified: 2010-05-18
We're running both VNC and PC Anywhere as a remote access utilities on quite a few machines.  We have the routers across the board with the same firewall access rules.  All routers also connect to a VPN server via IPSec.

We have one remote unit that works fine for web, vpn, etc.  However, when we conntect via VNC or PC Anywhere, we simply get a black screen after authenticating.  Oddly, if we plug in locally or tunnel in via VPN to connect w/ VNC or Pc Anywhere it works fine.

So... we're thinking it's the efficient 4100 DSL Modem?  Maybe, we're not sure.  We don't think it's our router, as we have the same settings everywhere and we've already played with settings, including MTU and fragmented packet handling.

It just doesn't make sense that it works locally and through the VPN.  Our ISP of course refuses to take any heat and claims the FIREWALL is off on their router (the Efficient).

And yes, we even replaced the PC.


Ideas? Thanks.
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Question by:jgantes
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by:Booda2us
ID: 17199210
Since it's just the one remote with the problem, thats the start of the hunt.  Is it the only unit using the 4100 modem?
>We have one remote unit that works fine for web, vpn, etc. <  Modem allows web browsing using what protocols? TCP/IP?
The pcAnywhere program uses User Datagram Protocol (UDP) Port 5632 to discover a host. Make sure UDP and port 5632 are enabled. Hope this helps..Booda2us
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by:jgantes
ID: 17200933
Turned out to be a an issue w/ MTU on multiple ends, including the ISP.  Oddly, their PPPoE was causing problems so the MTU had to be adjusted on our PC (Create a new DWORD key) their routers and our router too.


Thanks.
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Booda2us earned 300 total points
ID: 17209030
glad you fixed it..
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