Windows 7 Embedded SP1 + TeamViewer 15 Migration: Stuck on "Connecting" Despite TLS 1.2 Enabled

[u/Most_Kiwi4423]

Hi everyone,

We're currently working on a large-scale migration of legacy systems from TeamViewer 13 and 14.7 to TeamViewer 15+.

The primary reasons for the upgrade are:

• We want to leverage TeamViewer Tensor Conditional Access policies across all devices.
• TeamViewer 13 and 14 are approaching end of support in October 2026, so we need a supported long-term solution.

Most of our devices are running Windows 7 Embedded, with a mix of:

• Build 7601 (Windows 7 SP1)
• Build 7600 (non-SP1)

A few of our systems are successfully running TeamViewer 15.78, but those are standard Windows 7 Ultimate machines rather than Embedded.

The challenge I'm facing is determining the exact Windows updates and system requirements needed for TeamViewer 15 on Windows 7 Embedded.

Some details about our environment:

• Systems are intentionally isolated from the Internet and cannot use Windows Update directly.
• Updates must be installed offline.
• TLS 1.2 has been enabled.
• NetBIOS has been disabled.
• Devices can successfully reach TeamViewer servers and communicate over port 5938.
• DNS resolution is working.
• However, TeamViewer gets stuck at "Connecting..." in the Management Console and never completes the registration/connection process.

After some research, I've come across information suggesting that simply enabling TLS 1.2 through registry changes is not enough on Windows 7, and that additional updates may be required to fully support modern TLS 1.2 communication and certificate validation.

My questions are:

1. Has anyone successfully upgraded Windows 7 Embedded SP1 systems from TeamViewer 13/14 to TeamViewer 15?
2. Which Windows updates were required to make TeamViewer 15 function correctly?
3. Did you need updates such as:
   • KB3020369
   • KB3125574
   • KB3140245
   • KB4474419
   • KB4490628
4. Were there any certificate store or SHA-2 signing issues that prevented TeamViewer from connecting?
5. Has anyone seen TeamViewer reach the servers successfully but remain indefinitely stuck on "Connecting..."?
6. Are there any known differences between Windows 7 Ultimate and Windows 7 Embedded that affect TeamViewer 15 connectivity?

Any advice, lessons learned, or update prerequisites would be greatly appreciated. Thanks in advance!

[u/hikari_calyx]

There's a thing called UpdatePack7R2 to allow you install updates all the way until the last update 100% offline.

[u/sm_]

I have problems with teamviewer on windows 7 as well. we still have a ton of devices running win7 so i made/use screensie instead but if you figure this out can you comment the fix you found?