NAT type and RDP Shortpath - MX75

[MichaelN]

Hello,

I am trying to troubleshoot an issue with Azure Virtual Desktop clients, that are behind an MX75 appliance, in which the clients experience issues like frequent disconnects, and in overall low reliability of the connection. AVD logs contain errors like:

RDStack

ShortpathTransportNetworkDrop

The session host lost connection to the client because of an unexpected network error in the Shortpath transport. Check your network quality and configurations, then try again.

Client

ShortpathNetworkDrop

UDP: The client network connection to the Windows Virtual Desktop service was lost.

I am trying to find more information on this issue. Uplink packet loss and latency for this location is around 10-20ms, and 1-2%. 

Preferred way of AVD RDP client communication is by using UDP RDP Shortpath (described here: RDP Shortpath for Azure Virtual Desktop ), which should reduce latency and in overall improve user experience. 

I have run a network troubleshooting tool provided by Microsoft (called avdnettest) and the result is as following:

AVD Network Test Version 1.2303.10002.e62c947
Checking DNS service ... OK
Checking TURN support ... OK
Checking ACS server 20.202.68.96:3478 ... OK
Checking ACS server 20.202.68.91:3478 ... OK

Your NAT type appears to be 'symmetric', but you have access to TURN servers.
Shortpath for public networks is likely to work on this host.

See https://go.micosoft.com/fwlink/?linkid=2204021 for more information.
Press any key to continue ...

If i run this tool repeatedly, it gives mixed results:

AVD Network Test Version 1.2303.10002.e62c947
Checking DNS service ... OK
Checking TURN support ... OK
Checking ACS server 20.202.1.198:3478 ... OK
Checking ACS server 20.202.1.171:3478 ... OK

Your have access to TURN servers and your NAT type appears to be 'cone shaped'.
Shortpath for public networks is very likely to work on this host.

See https://go.micosoft.com/fwlink/?linkid=2204021 for more information.
Press any key to continue ...

Not sure why it shows "symmetric" and "Cone shaped" randomly.

Can someone please let me know if this appliance is using a Symmetric NAT or Cone-shaped NAT?

Is using RDP (UDP) Shortpath supported with this appliance?

The reason is that if RDP (UDP) Shortpath is not supported with Symmetric NAT, it would force me to use TCP for AVD clients.

Many thanks.

[alemabrahao]

Have you contacted Meraki support for help?

If you haven't, I recommend you do so. They will have greater visibility into your environment.

[MichaelN]

Thank you, I will contact Meraki support.

[PhilipDAth]

I think this might be related to this recent Microsoft bug.

https://www.bleepingcomputer.com/news/microsoft/microsoft-recent-windows-updates-cause-remote-deskto...

[IvanJukic]

Hi @MichaelN ,

"Uplink packet loss and latency for this location is around 10-20ms, and 1-2%."

Packet loss at 1-2 % may not seem much. But with TCP it is a lot. I would focus here on eliminating the Uplink packet loss. Try changing cables, checked Traffic Shaping with ISP. Run ping tests to various end points (Public DNS Servers, ISP Gateway & DNS, any popular Internet site of choice). This will give you a good benchmark to confirm if the 1-2% is consistent or transient.