Remote Desktop / VPN Issue

[mc_blue]

Hello all,

Our VPN runs through a Fortinet device with Fortiguard software. Basically, I login on the Fortiguard and then Remote Desktop onto the PC or I can view DVR CCTV footage. One of the PCs will not let me remote desktop now, basically I am prompted by the login screen and when I enter the username and password it freezes then the remote desktop window goes blank and closes itself. I've tried putting in the wrong password, the remote desktop responds like normal and asks me to input the right information... When I do it freezes again. :?

My VPN still works on other IP Addresses/PCs. The only change I've made to this PC is I've had to upgrade a user account from Limited to Administrator - would that have done something? I've tried logging in on both accounts to no avail.

Regards

[Marshy]

mc_blue said:

One of the PCs will not let me remote desktop now, basically I am prompted by the login screen and when I enter the username and password it freezes then the remote desktop window goes blank and closes itself. I've tried putting in the wrong password, the remote desktop responds like normal and asks me to input the right information... When I do it freezes again. :?

Has the machine that doesn't work had any service packs recently? This sounds like an MTU issue.

MTU - Maximum Transmission Unit - is the maximum size one contiguous piece of data on the network can be. If your data is bigger, it needs to be broken up into MTU-sized pieces. Running a VPN reduces the effective MTU. There's a mechanism to cope with this, but Microsoft broke it in a service pack or hotfix a while ago. It's since been sorted, but the machine you're trying to work with has 'got broken' in this way, you'll see what you describe: you can log in via remote desktop, but as soon as it tries to send you all the data that makes up the screen, it sends out a huge stream of packets at max MTU, doesn't notice that it's being told to reduce the size of its packets (due to the VPN) and everything falls on the floor before it gets to you. Hence, your client shows a black screen, and gives up after a few minutes.

Could also be caused by a botched firewall change.

[mc_blue]

Cheers - I'll check it out next time I'm in Birmingham.

Does have two admin accounts (one upgraded from limited) make any difference in itself?