Registering Microtik Gateway says it's been already registered

Hi Jeff, thanks for your quick reply.
I did search indeed, found some threads about people saying their EUI was already redistered like this one:

In those threads I did understand that it was necessary for someone who had already registered the EUI to delete their gateway or someone for the team did reply that they would delete cause it was not in use.
Anyway if I understood from your answer, I could choose a different EUI for my gateway.
I did set it on the gateway:

imagen

Unfortunately this way the gateway isn’t connecting:
imagen

The guide by Microtik tells to use the default Gateway Id (which is the same as the Hardware Id) as EUI:

Also I found this thread from a user of a different Microtik gateway having a problem when using a Gateway id different from the Hardware id:

The gateway is connected to the internet, lora is configured properly, so I guess the problem is the same as user ether had, but as I can not edit Hardware Id, and that Id is already in use I don’t see a workaround.

Thanks