I had this issue for the first time with a different hosting company. They say the same thing: the player must already have been on the server once in order for the admin to be able to whitelist them.
It's not true though. I had trouble whitelisting a brand new player, but I also had trouble whitelisting an existing player whom I'd removed just to see if I could whitelist him again (poor guineapig).
The host says it's a common problem and recommended removing the whitelist.json file and rebuilding it from scratch. That got 25 percent of the players off the whitelist: I couldn't add them back ingame or from the console.
However, I waited for 6 hours and tried again, and hey presto I was suddenly able to add all of them ingame!
So I'd say this is somehow an issue to do with the (connection with the) nameservers
eisenia
I had this issue for the first time with a different hosting company. They say the same thing: the player must already have been on the server once in order for the admin to be able to whitelist them.
It's not true though. I had trouble whitelisting a brand new player, but I also had trouble whitelisting an existing player whom I'd removed just to see if I could whitelist him again (poor guineapig).
The host says it's a common problem and recommended removing the whitelist.json file and rebuilding it from scratch. That got 25 percent of the players off the whitelist: I couldn't add them back ingame or from the console.
However, I waited for 6 hours and tried again, and hey presto I was suddenly able to add all of them ingame!
So I'd say this is somehow an issue to do with the (connection with the) nameservers