Integrating Keycloak with Spring Boot hit Exception

[james jodan]

I am trying quay.io/keycloak/keycloak:17.0.0. with a resource server running on Spring Boot. With the unsecured keycloak port 8080, token verification is fine. With secured 8443 link, when trying to get access to a resource, I got the following exception,

org.springframework.security.authentication.AuthenticationServiceException: An error occurred while attempting to decode the Jwt: Couldn't retrieve remote JWK set: org.springframework.web.client.ResourceAccessException: I/O error on GET request for "https://192.168.100.10:8443/realms/external/protocol/openid-connect/certs": No subject alternative names present
        at org.springframework.security.oauth2.server.resource.authentication.JwtAuthenticationProvider.getJwt(JwtAuthenticationProvider.java:106) ~[spring-security-oauth2-resource-server-6.1.2.jar!/:6.1.2]
        at org.springframework.security.oauth2.server.resource.authentication.JwtAuthenticationProvider.authenticate(JwtAuthenticationProvider.java:88) ~[spring-security-oauth2-resource-server-6.1.2.jar!/:6.1.2]
        at org.springframework.security.authentication.ProviderManager.authenticate(ProviderManager.java:182) ~[spring-security-core-6.1.2.jar!/:6.1.2]
        at org.springframework.security.oauth2.server.resource.web.authentication.BearerTokenAuthenticationFilter.doFilterInternal(BearerTokenAuthenticationFilter.java:137) ~[spring-security-oauth2-resource-server-6.1.2.jar!/:6.1.2]

 ........

Caused by: java.security.cert.CertificateException: No subject alternative names present
        at java.base/sun.security.util.HostnameChecker.matchIP(HostnameChecker.java:142) ~[na:na]
        at java.base/sun.security.util.HostnameChecker.match(HostnameChecker.java:101) ~[na:na]
        at java.base/sun.security.ssl.X509TrustManagerImpl.checkIdentity(X509TrustManagerImpl.java:458) ~[na:na]
        at java.base/sun.security.ssl.X509TrustManagerImpl.checkIdentity(X509TrustManagerImpl.java:432) ~[na:na]
        at java.base/sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:238) ~[na:na]
        at java.base/sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:132) ~[na:na]
        at java.base/sun.security.ssl.CertificateMessage$T13CertificateConsumer.checkServerCerts(CertificateMessage.java:1341) ~[na:na]

Could anybody help whether this is a configuration issue? I have changed nothing but http to https and 8080 to 8443. 

Thanks,

James