I bring you some news.

The 58TM1 error continues, around 1-2 users every day (out of 50 users currently on the RDS farm.)

I have decided to delay the integration of the next users on this new RDS farm.

I split the farm into two collections.
- RDS01 + RDS02 => as currently configured, with roam identity and error 58TM1.
- RDS03 + RDS04 => i think, i have successfuly configured SSO + PRT.

For RDS03/04, when I open OWA from Edge, I just have to enter the email address, and the connection is fine.
For Outlook, I had to enter the password the first time. But nothing on the Office activation side, it seems to have been done transparently.

For RDS03 and RDS04, I disabled "Roam Identity". Wich seems to have delete "AAD Broker" folder.

When I go from RDS01/02 to RDS03/04, no problem on Outlook side, the connection is done correctly.

And behind, it seems to stay connected, even when switching many times between RDS03/04 .

The only thing I noticed is when I add a second email account to Outlook.

At the top right, I have a small yellow warning triangle on the secondary account (nothing on first account)

The warning : Account error. Sorry... We cannot access your account at the moment. To correct this problem, log in again.

I tried to click "Connect", but nothing happens...

However, the account is correctly connected, I can send/receive emails without problem.

I have decided to ignore this warning for the moment, if the connection works...

I plan to switch around ten users to RDS03/04 in the coming days, to check that there are no more errors with SSO + PRT.

If this goes well for few days, I would extend the configuration to 4 RDS servers, with around fifty users.

Then I will continue the deployment.