RDS 2019 deployment - unable to add second RD Broker -

We are running a seperate RDS deployment for our 2019 servers. We had 2 brokers, gateways and RDWeb, with the three roles on one machine each. On our SQL cluster we have a database, where the nodes connect to. One of the brokers started acting up after some Windows updates, and finally it refused to work anymore. Do I just removed it from the deployment, updated our load balancers and currently we are running on one broker/gateway/rdweb just fine. But I want to add a second node again.

When I do so I get the following error:

The list of joined nodes could not be retrieved on <the machine I try to add as second broker>. Privilege not held.



So far I've tried:

- With the broker-dns entry with and without the second node in;

- after removing the old node (new one has the same name) I verified in the SQL database, the old server is NOT in there anymore;

- Firewalls all wide open while adding the node; even if no blocks were logged at al;

- Added the computer account of the new node to SQL and allowed it access to the DB, even we use username/pass as seems to be required in a HA setup.

The SQL connection string is fine by the way, for one the remaining node works fine and until recently it worked fine for the seconde node as well.

How to fix this? Any clue?