ERPV error problem with VPN - Please help ...

[Jon Doe]

Here's a peculiar problem that I'm having.

1) I have a setup where I run a Win2003 server as a VPN server to access my network remotely. When I login it assigns me a fixed ip address on that network.

2) I have SC on a website that my clients can go to so they can get assistance. When they click it, it goes to a router on the same network as the Win2003 server and port forwards to the same IP address that the VPN server assigns me when I log in remotely.

This gives me the ability to be mobile but still be able to assist clients.

Here's the problem: When I put my laptop physically on the same network as the router and server and statically assign it the IP address in question, everything works great with SC. When I come in through the VPN server i get the screen on my laptop that says:

Connection failed: Error reading Protocol Version

Possible causes:
- ..... DSMPlugin
- ..... Viewer and server ....
- ..... Bad connection
(if gateways or routing were bad this wouldn't even show up on my laptop)

Now the first two don't matter because all I have to do is change how I enter the network and they work.

The "bad connection" one is suspect because I can do non-SC UltraVNC connections over it, plus I've set up remote access tests that connect at 100 megabits.

Something is happening at the Win2003 VPN server that messes it up. Now here's the frustrating part: It used to work this way. I just can't figure out what has changed to make it quit working. I even set up a new second win2003 VPN server to test this with so I could test in a lab environment, but no matter what I do the problem persists. I've turned off all firewalling and port filtering, etc.

Jon = Stumped on this one.

Otherwise, I really like SC and hope to keep using it to support my peeps.


I've read the FAQ, searched the forums, Heck I've done everything but beg, so ......

Now I guess I'm beggin'

Thanks, jon

[JDaus]

I have seen similar to this happen with SSH tunnels, and i believe that it is caused by the way the SSH server (VPN in your case) handles the packets, and "morphs" them ... it screws with the VNCviewer ... as it then thinks that altered packet is encrypted ...

havent found a solution, except to stop using SSHD the way i wanted to ... and just use it a little less secure ...

as for your problem ... I would try connecting using the SC from the local lan while your VPNed in ... (eliminate the NAT from your router)

if that works, you probably need to spend the cash to buy i router with VPN endpoint (concentrator) encorporated into it ... that shoul solve your "double NAT" problem

if that doesnt work ... i cant help (at the moment anyway)

[Jon Doe]

Thanks.

[redge]

2nd solution totally free solution

XP
update the tcp/ip stack to smaller packet from 1500 (default) to 1492 for VPN
use DrTCP for easy modify default value of tcp/ip stack

[matty-a]

Does the MTU need to be changed on the Viewer side or the SC.exe side or both?

[bevtech]

I would change it on both sides when vpn are used i use 1462 mostly but 1492 should...

Do a search for drtcp to change the MTU on the adapters..