Outlook disconnected on the Win10 client which have 2 NIC

Question

Outlook disconnected on the Win10 client which have 2 NIC

Chong 871

Hi Support,

We have win10 and win7 client using outlook 2016 to connect exchange 2016 server. All of the machine have 2 NIC, only one NIC (exchange network) have default gateway.

Sometime the Win 10 client outlook will disconnect suddenly. During problem occur, the machine can ping to exchange server, OWA also work. (The network icon in icon tray change to "No internet".) We need to disable the NIC and enable the NIC again, then the outlook resume. (the network icon show "connected")

This problem only happen on Win10 client, Win 7 client don't have issue. We tried to reinstall windows, outlook, and network driver, both can't solved the problem
Any idea?

Thanks
Chong

ChristyZhang-MSFT 26,126 Reputation points Microsoft External Staff

2021-06-29T10:10:49.907+00:00
Hi @Chong ,

In order to further identify the problem, please provide the following information for our better research:

Do you have some special settings when using NIC, such as VPN? If the VPN is turned on, according to my search, some users in some threads have encountered similar problems when using VPN. Please try to turn off the VPN to check if there're any differences.

What is your current version of windows 10 and outlook client(File > Office Account > About Outlook)? Please make sure you have upgraded your Outlook to the latest version.

Is there any error pop-up when outlook disconnects? And does this issue occur in all outlook clients of win10 system, or only for special outlook client?

To further confirm whether the problem is only related to the outlook client, please check if other websites and other programs run normally during problem occur, such as Chrome and Mail?
Chong 871 Reputation points

2021-07-01T01:53:29.647+00:00
Hi @ChristyZhang-MSFT ,

We didn’t use VPN. But these problem user machine is a hyper-v client machine.

Win10 is 20h2. Outlook is 2016 and latest updated

No error pop up. The outlook just disconnected.
Not all Win10 client, just the Win10 client which is hyper-v client and have 2 NIC.

Only outlook disconnected. Webmail by using different browser is OK. Other internal application also work.

We thinking to do relate to the NSCI features in Win10. When the NIC detect no internet connection then the outlook disconnected. But our client connect to exchange through internal network,

Thanks
Chong
ChristyZhang-MSFT 26,126 Reputation points Microsoft External Staff

2021-07-07T09:50:17.333+00:00

Hi all,

Thanks for both your detailed replies.

According to your description, I noticed that this issue seems only occur in a specific environment using Win10 20H2 version and 2 NIC, and Outlook client can work fine without any issues in normal Win10 and Win7. I did much research from the perspective of Outlook but could not found any options or settings related to Network settings. So, I’m afraid the key point of this issue is still related to the Network settings in Windows and I removed the Outlook tag from your post.

I tried some research on the NSCI you mentioned and found a thread, which mentioned some contents about network status display errors. Please check if it could help: NCSI False "no internet" status. Thanks for your understanding and hope your question will be resolved soon!
Chong 871 Reputation points

2021-07-13T03:55:35.057+00:00

Hi @ChristyZhang-MSFT ,

We tried disable the NSCI by registry but not work.

This is a bug of the Win10 20H2?
Any workaround from Microsoft can solve the issue? We cannot ask all user reset their NIC every time when the issue occur

Thanks

Best Regards
Chong

4 answers

Your answer

ChristyZhang-MSFT 26,126 Reputation points Microsoft External Staff

2021-06-29T10:10:49.907+00:00

Hi @Chong ,

In order to further identify the problem, please provide the following information for our better research:

Do you have some special settings when using NIC, such as VPN? If the VPN is turned on, according to my search, some users in some threads have encountered similar problems when using VPN. Please try to turn off the VPN to check if there're any differences.

What is your current version of windows 10 and outlook client(File > Office Account > About Outlook)? Please make sure you have upgraded your Outlook to the latest version.

Is there any error pop-up when outlook disconnects? And does this issue occur in all outlook clients of win10 system, or only for special outlook client?

To further confirm whether the problem is only related to the outlook client, please check if other websites and other programs run normally during problem occur, such as Chrome and Mail?
Chong 871 Reputation points

2021-07-01T01:53:29.647+00:00

Hi @ChristyZhang-MSFT ,

We didn’t use VPN. But these problem user machine is a hyper-v client machine.

Win10 is 20h2. Outlook is 2016 and latest updated

No error pop up. The outlook just disconnected.
Not all Win10 client, just the Win10 client which is hyper-v client and have 2 NIC.

Only outlook disconnected. Webmail by using different browser is OK. Other internal application also work.

We thinking to do relate to the NSCI features in Win10. When the NIC detect no internet connection then the outlook disconnected. But our client connect to exchange through internal network,

Thanks
Chong
ChristyZhang-MSFT 26,126 Reputation points Microsoft External Staff

2021-07-07T09:50:17.333+00:00

Hi all,

Thanks for both your detailed replies.

According to your description, I noticed that this issue seems only occur in a specific environment using Win10 20H2 version and 2 NIC, and Outlook client can work fine without any issues in normal Win10 and Win7. I did much research from the perspective of Outlook but could not found any options or settings related to Network settings. So, I’m afraid the key point of this issue is still related to the Network settings in Windows and I removed the Outlook tag from your post.

I tried some research on the NSCI you mentioned and found a thread, which mentioned some contents about network status display errors. Please check if it could help: NCSI False "no internet" status. Thanks for your understanding and hope your question will be resolved soon!
Chong 871 Reputation points

2021-07-13T03:55:35.057+00:00

Hi @ChristyZhang-MSFT ,

We tried disable the NSCI by registry but not work.

This is a bug of the Win10 20H2?
Any workaround from Microsoft can solve the issue? We cannot ask all user reset their NIC every time when the issue occur

Thanks

Best Regards
Chong

Answer 1

Hi @Chong and @ChristyZhang-MSFT

Some details from my environment where I'm facing the same issue...

Outlook shows disconnected at random upon opening. Once it shows disconnected, it will not re-connect with a restart of the program or the PC.
To fix, the user must close outlook, disable any NIC/network adapter other than the primary, then re-open Outlook - it will now connect to our exchange server correctly. The user can then re-enable the other NIC's they use (most of our workstations have at least one additional NIC)
We are running Outlook 2016 on Windows 10 20H2. Exchange server 2010 on Window server 2008 R2 (soon to upgrade to exch2016 on server 2016/2019)
We do not use VPN's, and the only type of machines I've seen the issue happen on thus far are physical workstations.
We have IPV6 disabled entirely on our network via a GPO - I've seen some other articles stating that setting machines to prefer IPV4 r disabling IPV6 entirely will resolve this issue, but not in our case.
For context, the environment this issue is occurring in is an air-gapped local network with no outside connection - just one Exchange server being used as Database and CAS.
OWA works completely fine.
No error popups at all, just the disconnected message in the bottom right Outlook tray. All other network-related functions of Windows work fine - shared network drives, printers, etc.

A permanent fix/patch would be awesome for this, as it seems to re-occur for some users at random intervals. I've only really seen grumblings of this issue on the internet in the past few months, so perhaps it is something to do with 20H2?

Answer 2

HKBBK 1

I have same porblem, It is appear on upgade to 20h2. We try to many soulution but can't really solve this problem. We only used the script to reset the network. The outlook connect will resume when reset the network.

Answer 3

@Chong - @ChristyZhang-MSFT - any news on this?

@HKBBK Thanks for the comment.

To update everyone - this issue is still persisting on at least one of the machines in our environment. I tried setting the network adapter priority of the correct IPv4 adapter via the network configuration in control panel and also by setting the InterfaceMetric via powershell - no dice on this either.

Really frustrating issue with no official solution still. I don't want to have to reimage or replace this user's PC but I'm thinking there is no other option at this point.

Side note: The issue persists even after I've updated to Exchange server 2016 CU21.

Answer 4

Igor Valencic 1

Any news on that issue?
We are facing absolute the same thing. We had Windows 1809 and updated it to 21H2. Works on all Workstations where only one NIC is active...
But this a no go, cause almost all developer have more then 2 NICS...
Thanks for help!

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Outlook disconnected on the Win10 client which have 2 NIC

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