RDP through OpenVPN; fine on Android.. trash on Windows

[ericarthurc]

So here is my setup; Static Public Ip (WAN); Sonicwall NSA 2600 firewall (dchp, dns, blah blah the works); Cisco PoE switch; then a Windows 2016 Server; and I am running a virtual ubuntu 16.04 server running OpenVPN in bridge mode (so it has a normal IP on the hdcp server; 192.168.1.225). I am running all the defaults with the OpenVPN server. I used "wget https://git.io/vpn -O openvpn-install.sh" script to quickly set it up. I make a couple client files (.ovpn). Here is my issue; if I connect to the VPN with my Android Phone and use the Microsoft RDP app to rdp into a server on the network it works great! No issues! No connection drops; great responsiveness. (Using any Windows Computer) If I connect to the OpenVPN server with my windows computer and I RDP into the server; it connects then instantly hangs. Then it says connection lost; and it never starts working. I have searched around and haven't found a resolve yet.

Also as a side note; I tried to connect to the OpenVPN server with my laptop running Ubuntu 16.04.3 and i was getting bad packet errors left and right and nothing worked there?

[novaflash]

This sounds suspiciously like an MTU problem to me, you should do some tests to see what the size of your MTU window is. It's probably lower than normal. You should then adjust the VPN tunnel configuration to match by adding something like mssfix 1300 to the server config directives field.

[ericarthurc]

This sounds suspiciously like an MTU problem to me, you should do some tests to see what the size of your MTU window is. It's probably lower than normal. You should then adjust the VPN tunnel configuration to match by adding something like mssfix 1300 to the server config directives field.

Oh okay, thanks for the info. I will give it a try when I get time. Thank you so much!

[ericarthurc]

Hey I looked up my MTU on everything and it's 1500. On my Android RDP through the VPN is perfect, even just tested it on a Mac and it's perfect. So clearly Windows is doing something wrong here. I use Windows as my daily driver so it's pretty essential for me and this is make or brake :/

[novaflash]

I am unconvinced it's an OpenVPN issue to be honest. I use OpenVPN daily with RDP all the time, never an issue, and I'm on Windows too. I suspect something with a firewall or with the connection itself. If it isn't MTU then it must be some firewall thing I suspect. Sorry, but there just isn't any known issue with OpenVPN with any protocol. OpenVPN doesn't mess with the data it transfers.

[ericarthurc]

I just tried using a different RDP program on Windows and it worked perfectly while connected through the VPN. Its the built in RDP client on Windows that is causing the problem. I just have no idea where to start fixing it or why it's causing the problem. The only network settings in the built in RDP client is RD gateway and a caching settings; I tried with different settings and same results; instant disconnection?

I just downloaded the remote desktop app made by Microsoft from the Windows Store.. and it literally works through the vpn... what the heck Microsoft haha.

[JimDandy]

Just out of interest and for future note, what version of RDP and Windows were giving you the issue?

[ericarthurc]

Just out of interest and for future note, what version of RDP and Windows were giving you the issue?

Windows 10 Pro
RDP 10.0.17017.1000

[JimDandy]

FYI--No issue with this setup:

Win 10 Ver 1703 (OS Build 15063.413)
Product version 10.0.15063.0

Out of interest, what Windows 10 build?

[ericarthurc]

Windows 10 Pro Insider Build 17017.rs_prerelease.171010-1400

Never thought it could be a windows insider issue; but maybe?

My main desktop is not on insider and still has the same problem.

[novaflash]

That's certainly very interesting. But yeah, a preview version of an OS is bound to have some issues. Glad to hear that it wasn't OpenVPN's fault.