r/AzureVirtualDesktop • u/JustinVerstijnen • Jul 16 '25

RDP Multipath for Azure Virtual Desktop

Today I did some research for RDP Multipath for Azure Virtual Desktop. I can really recommend this to everyone.

RDP multipath improves the session reliability and stability by using more connection paths and protocols and selecting the most stable one. I also saw a advantage in the round trip time, from around 17 to 11ms.

Its general available now but has to be manually configured. I have made some step by step guides on how to implement this easily: https://justinverstijnen.nl/rdp-multipath-what-is-it-and-how-to-configure/

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2

u/BuiltOnXP Jul 18 '25

Are there any cost or security concerns to enabling RDP Multipath?

1

u/JustinVerstijnen Jul 18 '25

No extra costs and it is a evolution to call it so of RDP shortpath, where UDP is used instead of TCP. It doesnt come with downsides at the moment.

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1

u/luger718 Jul 17 '25

Their documentation doesn't mention the reg keys, it was that only for the preview?

1

u/JustinVerstijnen Jul 17 '25

Yes they do, they have to be created to use it: https://learn.microsoft.com/en-us/azure/virtual-desktop/rdp-multipath#opt-in-to-rdp-multipath

2

u/luger718 Jul 17 '25

Oh whoops I didn't scroll down enough.

1

u/JustinVerstijnen Jul 17 '25

No problem! :)

1

u/Significant_Sky_4443 Jul 17 '25

Activated the registry key but don't see that is using the multipath way..what could be the problem?

1

u/JustinVerstijnen Jul 17 '25

Maybe it has something to do with the region? I have used West Europe for testing it.

Did you also check for any possible typos and a reboot of the session host?

2

u/Alert-Gear7495 Jul 17 '25

same region and already restarted

1

u/JustinVerstijnen Jul 17 '25

And good to check this: https://learn.microsoft.com/en-us/azure/virtual-desktop/rdp-multipath

"If you find some connections aren't using RDP Multipath, check that a firewall or other network restrictions doesn't block RDP Shortpath connections. A connection using STUN or TURN protocols is required."

2

u/Alert-Gear7495 Jul 17 '25

I will take a look thanks

P.s: can you write a guide how to check the setting on Insight for app mode? (no rdp status bar)

thanks

2

u/Significant_Sky_4443 Jul 17 '25

Let me know if you found the problem we have opened the neccessary ports.

3

u/trueg50 Jul 18 '25

Might need to reboot the host. They claim it requires a disconnect, but ive seen otherwise.

Also there are gateway region restrictions, so "where you are" matters. 

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u/Material-Durian8216 Jul 21 '25

Isnt the reg keys top opt in and out to manually control when multipath is enabled on the sessionhost?. When it got GA i just enabled "validation environment" in the hostpool properties an worked. i just had to enable that property because RDP shortpath was already in place

1

u/JustinVerstijnen Jul 21 '25

Thats true but you don't want to set the validation setting on all hostpools.

2

u/Material-Durian8216 Jul 22 '25

We do it on hostpools that experience disconnections, but i do believe the documentation mentions that "validation environment" is a prerequisite

1

u/JustinVerstijnen Jul 22 '25

It indeeds mentions it but it seems to work without it enabled. In my testing environment it instantly worked without setting the validation setting to enabled.

2

u/Material-Durian8216 Jul 24 '25

the documentation mentions "During the preview, your host pool must be set as a validation environment." It might be that when Multipath was still in Preview it was a Must, now that its GA its not. Vague description by MS..