Forum Discussion

Brass Contributor

Sep 30, 2020

Solved

Unable to switch to Teams-only mode

I tried to switch from Island mode to Teams-only mode. But the admin center is not accepting the setting. Why? The screenshot shows one of my demo tenants. But I have the exact same iss...

microsoft teams

ChrisHoardMVP
Sep 30, 2020
Hi Robert K

Could be an issue with the TAC. Try with Powershell

https://blog.bardalen.no/index.php/2020/05/25/how-to-upgrade-users-coexistence-mode-to-teams-only-using-powershell/

Let me know how you get on. Hope this answers your question

Best, Chris

PelicanRichard

Copper Contributor

Apr 18, 2021

Hi Robert K,

From reading this thread it seems there are a few solutions to this but my issue turned out to be having multiple domains registered to my tenant. My default domain had the required DNS records (see attached) but the others didn't and that was preventing the switch, even though all individual users had already been switched to Teams Only via the TAC.

I deleted the non-default domains as we didn't use them anymore and that worked but I imagine adding the same DNS records to them would also have solved the problem if they were needed.

Hope that helps anyone else with the issue.

slate9

Copper Contributor

Jun 10, 2021

Hey , this thread is awesome and it looks like at the end of the day if the SfB DNS Entries aren't pointed to O365 services then it will fail.

In my case Cloudflare's DNS Caching was enabled for both the SIP and lyncdiscover entries. Once I disabled DNS Caching in Cloudflare, the Domains area in o365 Admin Portal had all checks and the TAC Coexistance mode was able to be changed.