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“Can’t sign in to Skype for Business
The server is temporarily unavailable.” the basics.
I have come across this error message more often. We have already created a Microsoft Premier ticket numerous times for this problem at the office. I know of two solutions and the third one can be used to troubleshoot the problem.
Because I assume that only system administrators maintain Skype for Business, the blog post does not consist of screenshots.
Is IPV6 enabled in your environment?
By default, Skype for Business is not enabled for IPv6. This only works when Microsoft sets this for your tenant. Make sure that your network is not IPv6 or that your tenant is otherwise enabled for IPv6. So unless it’s not enabled, make sure that S4B traffic goes over IPv4.
You can check whether your network is IPv4 in the following ways:
- Check whether your network adapter on your windows device is not just enabled for IPv6, and otherwise you can re-enable IPv4.
- Open command prompt and run a NSLOOKUP to sipdir.online.lync.com, if the traffic comes back over IPv6 then you know that IPv6 is enabled.
Skype for Business and IPv6
Microsoft will enable IPv6 for Skype for Business at your request in the public multi-tenant cloud and in Office 365 Government G1/G3/G4/K1 subscriptions. After it’s enabled, if the program that you use to connect to Skype for Business supports IPv6, it will use IPv6 by default. If you want to control communications to Skype for Business, use the IP address ranges in Office 365 URLs and IP address ranges.
Please be aware IPv6 is not available in all regions and Microsoft may not be able to activate it for your Tenant at this time.
The second is “MSOIdentityCRL” regkey.
“After having tried multiple Microsoft provided resolutions of deleting Lync profiles, temporary folders, cryptography keys, accountprofile.dat, delete sign-in info, etc., their support team had us kill the Lync process completely and then delete the whole HKCU\Software\Microsoft\MSOIdentityCRL key. and then start up Lync. And then it started working properly and we replicated the fix on the remaining affected profiles.”
For those not so familiar with Registery Editor I’ve made a small tutorial with screenshots.
Right click start and click on Run or press Windows + R
Copy the register key: HKCU\Software\Microsoft\MSOIdentityCRL
And paste it in Registery Editor.
Right click MSOIdentityCRL and click Delete
Try to log on Skype for Business again and see if it worked.
The third option is the Microsoft Connectivity Test.
If neither of these two solutions solved your problem you can also try to run the Microsoft connectivity test.
This should give you the reason why your S4B is not connecting.
I know this error message is generic, so if you find another solution, could you share it in the comments?
If you have other comments or ideas, you can also indicate this below.