Troubleshoot Request VPN site-to-site connectivity issues

Question

Troubleshoot Request VPN site-to-site connectivity issues

Deepak Kumar 145

Hi Microsoft Team,

We are following up on this issue as the problem is still ongoing and impacting multiple users.

Summary of the issue:

Users experience frequent session freezes and automatic reconnects while working on the Sandwell VDI (every few minutes).

Error patterns observed:

Network unavailable error detected within 30 seconds of disconnect

What has already been validated:

Azure networking, NSGs, routing, latency, and VPN connectivity have been reviewed and confirmed healthy.

Continuous ping tests and Network Watcher diagnostics show stable reachability.

Microsoft diagnostics also confirmed no fault detected on the Azure S2S VPN or AVD infrastructure side.

Current status:

A formal Microsoft support ticket has now been raised for deeper investigation.

The client has requested a joint troubleshooting session with Microsoft, as the issue is affecting productivity.

We are prepared to grant consent for Microsoft to review both environments simultaneously if required.

Request from Microsoft:

Please advise on next-level diagnostics (AVD agent logs, session host telemetry, or known platform issues).

Let us know if this requires escalation to the Azure Virtual Desktop product/engineering team.

Guidance on correlating AVD disconnect events with client-side VM behavior would be appreciated.

We are keen to work closely with Microsoft to identify the root cause and implement a permanent fix.

Thank you for your continued support.

Kind regards, Deepak Kumar

Vallepu Venkateswarlu 10,595 Reputation points Microsoft External Staff Moderator

2026-01-27T12:48:14.6133333+00:00

Hi Deepak Kumar,

Thank you for contacting us about the AVD issue. We have begun looking into it and will share our suggestions with you as soon as possible. If you have any additional details or concerns in the meantime, please let us know. We appreciate your patience while we work on this.
Deepak Kumar 145 Reputation points

2026-01-27T12:51:01.1566667+00:00

Thanks Vallepu, We'd like to connect on MS teams call to check it further.
Vallepu Venkateswarlu 10,595 Reputation points Microsoft External Staff Moderator

2026-01-27T13:23:00.45+00:00

Hi Deepak Kumar, Can you please share the requested details in Private message so we can proceed with the Teams call?
Deepak Kumar 145 Reputation points

2026-01-27T15:40:52.5366667+00:00

Hi Venkat, I shared the relevant info. as requested for tomorrow's call.
Manish Deshpande 8,215 Reputation points Microsoft External Staff Moderator

2026-02-24T16:44:45.06+00:00

Hello Deepak

I have shared some information regarding the status on the private message.
Manish Deshpande 8,215 Reputation points Microsoft External Staff Moderator

2026-03-03T06:25:51.2633333+00:00

Hello Deepak

The Engineering team would like to connect with you. I have sent an email requesting your availability.
Manish Deshpande 8,215 Reputation points Microsoft External Staff Moderator

2026-03-03T08:34:00.7833333+00:00

Joined the call and User confirmed that VPN is not installed.

User is not using any VPN and found that RTT (Round trip time is high to 180ms) Hosted in UK West region.

Followed the link to fix the customer issue.

https://learn.microsoft.com/en-us/troubleshoot/azure/virtual-desktop/troubleshoot-connection-quality
Manish Deshpande 8,215 Reputation points Microsoft External Staff Moderator

2026-03-19T03:50:46.2933333+00:00
Joined the call along with the AVD (Collab team)

RTT was measured at ~180–270 ms.

Ideally, RTT should be under 100 ms; higher latency can cause frequent disconnections.

The main reason is regional distance:

AVD session hosts are located in UK West

Users are connecting from India (and some from the UK)

This cross-region access increases latency, especially when users run Teams, browsers, or other applications at the same time.

To resolve this, either users should access AVD from the same or a nearby region as the session hosts, or session hosts should be deployed closer to the users’ location.

Creating two host pools—one in India and one in the UK—would address this issue.

1 answer

Your answer

Vallepu Venkateswarlu 10,595 Reputation points Microsoft External Staff Moderator

2026-01-27T12:48:14.6133333+00:00

Hi Deepak Kumar,

Thank you for contacting us about the AVD issue. We have begun looking into it and will share our suggestions with you as soon as possible. If you have any additional details or concerns in the meantime, please let us know. We appreciate your patience while we work on this.
Deepak Kumar 145 Reputation points

2026-01-27T12:51:01.1566667+00:00

Thanks Vallepu, We'd like to connect on MS teams call to check it further.
Vallepu Venkateswarlu 10,595 Reputation points Microsoft External Staff Moderator

2026-01-27T13:23:00.45+00:00

Hi Deepak Kumar, Can you please share the requested details in Private message so we can proceed with the Teams call?
Deepak Kumar 145 Reputation points

2026-01-27T15:40:52.5366667+00:00

Hi Venkat, I shared the relevant info. as requested for tomorrow's call.
Manish Deshpande 8,215 Reputation points Microsoft External Staff Moderator

2026-02-24T16:44:45.06+00:00

Hello Deepak

I have shared some information regarding the status on the private message.
Manish Deshpande 8,215 Reputation points Microsoft External Staff Moderator

2026-03-03T06:25:51.2633333+00:00

Hello Deepak

The Engineering team would like to connect with you. I have sent an email requesting your availability.
Manish Deshpande 8,215 Reputation points Microsoft External Staff Moderator

2026-03-03T08:34:00.7833333+00:00

Joined the call and User confirmed that VPN is not installed.

User is not using any VPN and found that RTT (Round trip time is high to 180ms) Hosted in UK West region.

Followed the link to fix the customer issue.

https://learn.microsoft.com/en-us/troubleshoot/azure/virtual-desktop/troubleshoot-connection-quality
Manish Deshpande 8,215 Reputation points Microsoft External Staff Moderator

2026-03-19T03:50:46.2933333+00:00

Joined the call along with the AVD (Collab team)

RTT was measured at ~180–270 ms.

Ideally, RTT should be under 100 ms; higher latency can cause frequent disconnections.

The main reason is regional distance:

AVD session hosts are located in UK West

Users are connecting from India (and some from the UK)

This cross-region access increases latency, especially when users run Teams, browsers, or other applications at the same time.

To resolve this, either users should access AVD from the same or a nearby region as the session hosts, or session hosts should be deployed closer to the users’ location.

Creating two host pools—one in India and one in the UK—would address this issue.

Answer 1

To troubleshoot the ongoing site-to-site VPN connectivity issues impacting users on the Sandwell VDI, consider the following next-level diagnostics and steps:

AVD Agent Logs: Collect logs from the Azure Virtual Desktop (AVD) agents on the session hosts. This can provide insights into any errors or warnings that occur during the session freezes or reconnects.
Session Host Telemetry: Review telemetry data from the session hosts. Look for patterns or spikes in resource usage (CPU, memory, network) that coincide with the disconnect events.
Network Watcher Diagnostics: Since you have already confirmed stable reachability, ensure that the Network Watcher diagnostics are set up to monitor the specific traffic patterns and check for any anomalies during the disconnects.
User-Defined Routes (UDR) and Network Security Groups (NSGs): Double-check the configurations for UDRs and NSGs on the gateway subnet. Sometimes, misconfigurations can lead to intermittent connectivity issues. Removing any unnecessary UDRs or NSGs temporarily can help isolate the problem.
Perfect Forward Secrecy: If applicable, verify whether the on-premises VPN device has Perfect Forward Secrecy enabled, as this can cause disconnection issues. If it is enabled, consider disabling it and updating the VPN gateway IPsec policy.
Correlation with Client-Side Behavior: Investigate if there are any client-side VM behaviors that correlate with the disconnect events. This can include checking for any local network issues, firewall settings, or VPN client configurations that might be affecting connectivity.
Escalation to Azure Virtual Desktop Team: If the above diagnostics do not yield results, it may be necessary to escalate the issue to the Azure Virtual Desktop product/engineering team for deeper investigation.

By following these steps and collaborating closely with Microsoft support, you should be able to identify the root cause of the connectivity issues and work towards a resolution.

References: