Keycloak 26.4.0 container not saving user credentials or deletions when accessed via custom domain (works with localhost) [closed]

I’m running Keycloak 26.4.0 in Docker on Ubuntu.
PostgreSQL is running in another container on the same Docker network.

When I access Keycloak via https://localhost:8443, everything works fine:

• I can create, edit, and delete users.

• Password updates persist in the database.

However, when I access the same container using my domain name
👉https://identity.atlas.works.com:8443
the admin console behaves strangely:

• I can log in successfully.

• Creating a user appears to succeed (green success message).

• But passwords don’t get saved, and deleting users does nothing.

• PostgreSQL shows no updates when these actions happen.

• Same with MSSQL database.

This is my SETUP :

sudo docker run -d --name keycloak \  -v /opt/KCSetupT/certs:/opt/keycloak/certs \  -e KC_DB=postgres \  -e KC_DB_URL=jdbc:postgresql://keycloak_postgres:5432/keycloak \  -e KC_DB_USERNAME=keycloak \  -e KC_DB_PASSWORD=mypassword \   -e KC_PROXY=none \  -e KC_HTTPS_CERTIFICATE_FILE=/opt/keycloak/certs/identity_atlas.crt \  -e KC_HTTPS_CERTIFICATE_KEY_FILE=/opt/keycloak/certs/identity_atlas.key \  -e KC_HOSTNAME=identity.atlas.works.com \  -e KC_HOSTNAME_STRICT=false \  -e KC_BOOTSTRAP_ADMIN_USERNAME=admin \  -e KC_BOOTSTRAP_ADMIN_PASSWORD=admin \  -p 8443:8443 \  --network kcsetup_default \  quay.io/keycloak/keycloak:26.4.0 start

I also tried adding:

--add-host identity.atlas.meci.gov.cy:10.111.222.42

Where IP is my VM IP where docker is running but the issue persists — same behaviour.

NOTE: I am not using any proxy Its just VM where docker is running and I try to access KC with domain name. Host files has been updated as well.

What I’ve verified:

• Database connection is OK (kc show-config confirms the JDBC URL).

• Certificates load successfully and HTTPS works.

• The Keycloak logs show no errors (only standard startup info).

• I can access Keycloak from inside the VM using both localhost and the domain.

• But user admin actions (password/deletion) never persist when using the domain.

Question:

Why does Keycloak 26.4.0 fail to persist admin actions (like setting passwords or deleting users)
when accessed via a domain name instead of localhost, even though DB connectivity and certificates are correct?

Is this related to Keycloak’s KC_PROXY mode, hostname validation, or some internal HTTPS loopback issue?
What is the correct way to configure Keycloak in Docker to make it work properly with a domain name?

Before someone mentions that similar questions already exist, please note that there are two different questions on Stack Overflow.

The first one is about a database connection issue, which is not related to my case. In my setup, Keycloak successfully saves data to the database, and I can see the tables. When I create a new user, it appears correctly. However, when I try to add a password, it fails to save the password in the database, also all other setting settings I change like delete user.

The second question is about a GCP domain issue (server not found). In my case, Keycloak is accessible via the domain, and I can even log in.

So, my question is unique.