Realms connection: white-list issue

I am whitelisted for this server but am not able to log into Realms consistently. Been shown "You aren't white-listed on this Server" message incorrectly and inconsistently for past few weeks. And if trying to use the quick launcher it shows " Failed to quick play.  Lacking permission to connect to this Realm" 

 

Most recent session was less than 24 hours before this was shown again. Sometimes I am able to log in multiple times a day with no problem. And sometimes I am not able to log in after a previous session within 24 hours and have to wait from anywhere between 1-10 hours  before I am allowed to connect to the server again. 

I do not own this Realms server and it has been confirmed that I am not removed from the server white-list, nor was the server offline.