A game I develop for is having the same issue, the max players is 20, but peaks at about 10 players per server and having like 5 servers.
Strange, huge games always have full spots on the top servers.Gotta scroll down pretty far to find an open server. Might just be a small game thing.
I believe this is due to players joining their friends which results in the server going above what the ‘optimized limit’ is. Larger games have more total players and therefore have a greater chance of friends meeting up to play together.
I’ve had these issues before.
I mean a clear time this has occured for me is when the games first start and two players create a server (at that point the servers are just there and I close the other one down). Second time is when a game has been extremely laggy and I have generally found if I keep rejoining the same game I eventually get a new server. This is likely done by something on Roblox’s end in order to assure a good game experience for a specific player - as such it might feel a need to have a second server. Hard to comment as I don’t work for Roblox and as such I don’t know how the server creation system works.
That kinda reasonable, I think it is somewhat to do with friends, but I also think it’s capping at 10 for another reason. Thanks for the help. 
This has never worked for me. I have a smallish(~600peak) game that operates on lobbies and it kills my game having 20 players spread among 2 or even 3 servers when a match needs 6+ players to start
Perhaps Roblox creates new servers for different locales?
That’s pretty unfriendly for smaller games then, and still doesnt abide by what their game property says
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