Exchange Problems to receive mails on Port 25

In case your Exchange is not reliable receiving Mails on Port 25.

Open ExchangeManagementConsole

Get-ReceiveConnector | Where-Object {$_.Bindings -like „*:25“} | fl Identity, Bindings, TransportRole

More than one entry with same Port as  Hubtransport?

Ok - map the Hubtransport to the correct TransportRole like:

Set-ReceiveConnector "Name of Your Hubtransport Relais" –TransportRole FrontEndTransport

Problem fixed!