Server 2019 Custom Port on Session Hosts

Hello All,

I am seeking help in understanding what ia m doing wrong :)

my current setup

3 servers, with the following roles

1-RDWeb with RDgateway- Dev01 - port 443

1- Broker and license and Session host -Dev02 - port 5589

1- Session host -Dev03 -port 6689

Inbound traffic on Dev02 and Dev04 are only allowed (full inbound) from RDWeb /GW 

Dev01-In Server Manager - Remote Desktop Services - Overview - Tasks - Deployment Properties you need to specify the external FQDN of your RD Gateway server.  If you have RDWeb and RDG on the same server this would be the same FQDN that your users will use for RDWeb.  For example, if your users use https://dev01.mydomain.com/rdweb to connect to your RD Web Access site, then you would enter dev01.mydomain.com for the RD Gateway name in deployment properties.

2 collections calculator published

testdev02 -> apps published from dev02

testdev03 -> apps published from dev03

Set-RDSessionCollectionConfiguration -CollectionName "Testdev03" -CustomRdpProperty "server port
:i:6689"

Set-RDSessionCollectionConfiguration -CollectionName "Testdev02" -CustomRdpProperty "server port
:i:5589"

RAP and CAP is really basic 

RAP->Brokers allowed on port 5589

RAP allowed to all network resources for both 5589 and port 6689

Issue:

I am publishing tha apps over the remotapps native client on Win10

If I try to Access Calculator from Dev03 i get the error 

Remote Desktop can't find the computer "Dev02" this might mean that "Dev02" does not belong to the specific network.Verify the computer name that you are trying to connect to.

If I try to access calculator from Dev02 everything works!

if I change the custom Port on Dev03 to 5589 and issue

Set-RDSessionCollectionConfiguration -CollectionName "Testdev03" -CustomRdpProperty "server port
:i:5589"

Refresh resources Calculator from Dev03 works!!

can someone hint /guide why i can't make the calculator work from Dev03 on a different port than the Broker cutom port? or eventually how to make that work :)

Ultimate Goal:

I want to set different ports on each Session Host Collection