OK, this has me stumped. I'm setting up an Arma3/Epoch Mod server rented from Survival Servers. I've placed the Ryan's Zombies distribution files in a folder at server root alongside @Epoch and @EpochHive named @RyansZombies. One level down there's the addons and keys folders and meta.cpp, mod.cpp, and mod.paa. In addons there's the unmodified distribution ryanzombies.pbo and the ryanzombies.pbo.RyanD.bisign files. I copied the key into the root keys folder. I've added dir = "@RyansZombies"; to the first line of mod.cpp, but that didn't change anything. My launch parameters include the mods fields

@Epoch;@EpochHive;@RyansZombies.

I've added ....

"ryanzombies",
"ryanzombiesfunctions"

to the addons[] array in mission.sqm.

There are no other mods. I have placed no spawners. I'm just trying to get the server up and running with the mod installed, but not yet used.

I've got tons of experience modding A2. This is my first A3 server.

Upon attempting to join, the player gets the message:

Session lost - file
'@RyansZombies\addons\ryanzombies.pbo' not
found.

Of course if it were session lost due to a verification error, it would be a missing key. But the key is installed. The file is THERE, but the server can't see it.

<minor epiphany>

Ah. Stupid me. It's not a message from the SERVER. It's a message from the CLIENT. The client has Ryan's Zombies and Demons installed by Steam invoked by A3L. The folder name is the mod number. The server is finding it just fine. The client doesn't know where to look unless I add it to the Epoch mod under Advanced manually. OK. Never mind. I've got this typed up so I'm going to leave it for anyone else to see. Clearly some thought has to go into consistent naming of folders between Steam-subscribed mods on the client side, automatic mod detection and loading, and server installations.