Installing Harbor in a docker environment behind LB


Hello community We are trying to use Harbor in a docker environment behind a LB (HA-PROXY) and integrate it with Keycloack.
It happens that we can't redirrect the call on the harbor instance to the dns defined in the keycloack giving us the error 400 mismatch.
When can we change the callback uri to match the dns created ? Because on the OIDC configuration it has defined the uri to point to the hostname.

We changed the external_url on the harbor.yaml and got no effect.. 
Has anyone been through this? 
Best, Regards