Remote desktop not working over VDSL

[Rouxenator]

This is a bit of a weird one.

In the past I have always been able to VPN to work and then RDP onto my workstation from home, either on my PC or on my Android phone. Recently I found that when I do that the screen is just black when I do a RDP connection and the I get an error that it can't connect.

I have tried with both Afrihost and Vox accounts. It works on my phone when I go via Vodacom (wifi off). It also works from my parents place, they are on Axxess ADSL.

So I am not sure if it is a router thing or because I am on VDSL? Router is an Asus DSL-AC52U.

any tips?

 

[Necropolis]

Try lower the MTU on the PC that you are launching MSTSC from.

Sounds very much like a router somewhere along the line is expecting a lower MTU and discarding your packets.

https://support.zen.co.uk/kb/Knowledgebase/Changing-the-MTU-size-in-Windows-Vista-7-or-8

edit:

And you can use this method to find an MTU that will work: https://kb.netgear.com/19863/Ping-Test-to-determine-Optimal-MTU-Size-on-Router .

 

[Rouxenator]

OK I'll give it a try. Weird thing is I can RDP from work to my home PC just fine.

 

[Necropolis]

OK I'll give it a try. Weird thing is I can RDP from work to my home PC just fine.

Sounds about right.

 

[Rouxenator]

So I did the ping thing, maxed out 1464, added 28 and what do you know, that is the MTU of the router? Or should I ping the VPN address instead?

 

[Necropolis]

So I did the ping thing, maxed out 1464, added 28 and what do you know, that is the MTU of the router? Or should I ping the VPN address instead?

Rather ping the VPN address.

 

[MickZA]

Don't if this helps but we've been using 1472 MTU on our IPCop IPSec VPN tunnels forever and never had a problem.

 

[Rouxenator]

I am connect to the VPN now, largest packet I can ping my workstation with is 1372, how can I tell the VPN connection or RDP to use that packet size?

 

[irBosOtter]

I am connect to the VPN now, largest packet I can ping my workstation with is 1372, how can I tell the VPN connection or RDP to use that packet size?

You will need to make that change on your router's WAN interface I think. What router do you have?

 

[Rouxenator]

Asus DSL-AC52U, everything works fine so I am trying to get remote desktop to use a smaller MTU

 

[Necropolis]

Asus DSL-AC52U, everything works fine so I am trying to get remote desktop to use a smaller MTU

set the MTU on the machine you are creating the remote desktop connection from.

 

[Rouxenator]

Microsoft Windows [Version 10.0.14393]
(c) 2016 Microsoft Corporation. All rights reserved.

C:\WINDOWS\system32>netsh interface ipv4 show interfaces

Idx     Met         MTU          State                Name
---  ----------  ----------  ------------  ---------------------------
 24          25        1400  connected     MiX STB
 14          25        1500  connected     Ethernet
  1          75  4294967295  connected     Loopback Pseudo-Interface 1


C:\WINDOWS\system32>

So the VPN connection is set to 1400, not sure if that is good or bad?

 

[Geoff.D]

You will need to make that change on your router's WAN interface I think. What router do you have?

On the machine from which you are trying to set up the VPN. Can't see at the moment why a change in service connection should have impacted on a working VPN. More to do with matching the PC and the router surely? One should be able to use a smaller MTU than the connection can handle?

 

[irBosOtter]

On the machine from which you are trying to set up the VPN. Can't see at the moment why a change in service connection should have impacted on a working VPN. More to do with matching the PC and the router surely? One should be able to use a smaller MTU than the connection can handle?

Yes ja I was reading the article in the link which states make the change on the router, that's why the "I think" is in there

 

[Necropolis]

On the machine from which you are trying to set up the VPN. Can't see at the moment why a change in service connection should have impacted on a working VPN. More to do with matching the PC and the router surely? One should be able to use a smaller MTU than the connection can handle?

Smaller - yes.

Bigger - and you get what Rouxenator is experiencing.

 

[irBosOtter]

Microsoft Windows [Version 10.0.14393]
(c) 2016 Microsoft Corporation. All rights reserved.

C:\WINDOWS\system32>netsh interface ipv4 show interfaces

Idx     Met         MTU          State                Name
---  ----------  ----------  ------------  ---------------------------
 24          25        1400  connected     MiX STB
 14          25        1500  connected     Ethernet
  1          75  4294967295  connected     Loopback Pseudo-Interface 1


C:\WINDOWS\system32>

So the VPN connection is set to 1400, not sure if that is good or bad?

Make it 1354 and try again if it's not working on 1400

 

[Rouxenator]

Tried 1354 and not luck. I wonder if I should try something low like 600.

Edit : 600 also did not work, I think this could be another issue, not MTU related.

 

[Necropolis]

Tried 1354 and not luck. I wonder if I should try something low like 600.

Give it a bash and if it works slowly increase it until it stops working then fall back to the last working value.

 

[Rouxenator]

I just connected a 3G USB dongle to the router and made that the internet connection, everything works fine. But now back on VDSL - nothing.

 

[irBosOtter]

I just connected a 3G USB dongle to the router and made that the internet connection, everything works fine. But now back on VDSL - nothing.

Just for interest sake, what it the MTU size on the Asus router under the PPPOE connection settings? By default it's 1492 according to their documentation