Arma 3 is a game designed around the possibility of modding and include multiplayer, both are perfectly compatible, but actually with the way it work it is really bad for player side and optionsless for server side.

We don't find a lot of "playable" server, most of them are empty, have high ping and when we find one we can't play on it cause he get trouble with mods.

When someone create a server with a list of mods how many chance we have to have the same mods installed and activated ?
I was already get ejected from server just because i have a single mods more or less.
Some server don't accept any mods at all and other accept all mods but we have no way to find which one do.

Most of the mods DON'T influence the gameplay, some of them add new weapon, units and except if the server use VAS or any other mods that permit to give to the player an access to every object mods like this DON'T influence the server, fix issue like visible DFS crosshairs or readable interface, FA GPS, other add immersion and again don't change at all the gameplay like JTD Flies, Alpha Sound, VTS Gesture and other try to fix leak of feature from dev like VTS Resting weapon (a game like arma with recoil, weapon sway and recoil without bipod use and resting it is really stupid and unrealistic) CMFix, Mag Repack.

It mean that most of the time we are rejected of the server for NOTHING.
Example here : i have try to join a server "Stratis Life mission", we have NO access to custom weapon/units and almost every other mods don't change the gameplay and they can't be considerate like an advantage or a cheat, it make no sense to become rejected by the server cause of this and it don't fix the cheaters/hackers issue anyway.
Almost every time when a server refuse player with more mods than him when we get rejected it is only cause the server creator PERSONALLY don't like the mods, don't see the use for HIM, are too lazy to download it or don't know about and for some player, mods can be important depending the way we play.
Fight against server list is on of the worst thing we can get and if we want to play a single time we have to get rejected by maybe 10 server, and sometime we don't get more than 15 server with more than 2 people inside and ping under 150

What i propose here is a way to fix it and reduce hackers in the same time and give more possibility to server.

Online mods check
Server side mods interface
Player side mods matching

Online mods check :
Rather than be stuck with server creator mods preference (when it don't influence gameplay) check mods not from the server but from online official server, like a mods check from Armaholic or any other things like this.
It mean no more issue cause the server don't include a single mods that we have or don't need for the server creator to download every mods.

Server side mods interface :
First thing, divide mods into category
_Those who don't add units/weapon and who don't change the gameplay, like those who only touch the interface/color or things like this.
_Those who only add things, like weapon/accessory pack, units, uniform and all other that anyway can't be access until the server use VAS or other "all item available" script/mods
_Those who fix issue, leak of feature, give more immersion/realism but don't influence the gameplay like Resting Weapon or Gesture, Alpha Sound etc.
_And those who change the gameplay like object manipulation/spawn, player characteristic or change vanilla feature like recoil and other
The server creator have access to a list divided into sub tabs :

Minor modification
Units/weapon/object adding
Gameplay minor change/immersion improvement
Gameplay change/unbalance/cheat like.

For each category have subcategory that permit to have access to precise mods type like for example with :
Units/weapon/object adding -> Units / vehicle / Weapons / Gear&attachments / Object pack.
Example with Weapons -> Pistol / MG / AR / SMG / Sniper Riffle / launcher / explosive / other,specials.

And then when we go inside a precise category we can see one by one all mods like all Pistol for example with a picture and a description.

The server creator are able to enable or disable a any category or subcategory.
Like disabled all MG or sniper mods or simply disabled a single one like a too powerful cal 50 sniper riffle or anything like this.
This will permit for Armaholic for example to become the reference that can include every mods (better for find it) and i don't know if Armaholic is official from BIS or not but i know that BIS moderator also mastering Armaholic, anyway it can permit to give a more official check of mods and avoid a lot of cheated by redlisting every mods that was not approval.
Possibility for the server creator to save the approved mod list for each mission and load it like he want rather than recreate it everytime he create a new server.

Now the most important part :
Player side mods matching :
When we expecting to go inside a server that use less mods than us or disable several mods that we have, rather than need to restart the game, make TWO different mods loading system :
On for single player with a list that we only want to use for single player
Another for multiplayer that load all mods that we have listed but with no mods preloading or with reloading.

It mean if we try to go inside a server with several mods that we have disabled, we will get something like :

The following mods are disabled from this server :
Mods1, Mods2, Mods3 etc...
Do you want to continue on this server without this mods ?

If we select no, we go to check another server, if we select yes it will load every mods we have EXCEPT those disabled on this server, no need to restart and manually disabled every mods everytime we want to joins a different server to match him, even if it need to reload some part of the game and take more time while matching with server list, it is better than manually disabled all mods (which is the most boring thing i have ever see in any multiplayer game) and restart the game.

The advantage to link the mods online check with Armaholic can be the downloading matching/patching, download mods that we don't have and the server do from Armaholic, exactly like the mission file was download/
It will permit to match with the server and with a "multiplayer download modsfolder" folder to keep the mods itself, several game do it, when we want to play in a server who have more mods than us we download missing files and they are put in a temporary mods folder.
The same system with an option that permit to empty this folder when we leave the game (except if it crash, the exit button start the command, not the game closing itself) or keep all this, that mean keep mission file with script and save, keep mods folder/files that we can use again on server rather than download it again.

And this system can also fix a last issue : Invisible mods
When someone don't have a mods and other do, we see invisible weapon/gearless people, rather than this, including a small "low definition texture and a low polygon number 3D object, or simply a long range LOD version" file size version, of course even if it can be great i don't talk about live modding that permit us to use the weapon mods, just a system that permit to see something better than a invisible mods/
With options : ->
OFF (use the closest vanilla equivalent, definite by modder) ->
ON (download small polygon number and low definition texture version of the mods) ->
ON and no purge (Same than ON but keep the file in the famous "multiplayer download modsfolder" when we leave the game, nice for those who don't care about the small HDD consummation that it take and don't need to download it again for those who will comeback on this server where people use a lot of different mods.

It mean that Armaholic will have 3 files per mods : Standard mods, Unzip / in game installation instructions / size limited version of the object like medium/long range LOD version.

Of course keeping a log file that list the mods downloaded from the server or the small LOD version of other user mods.
Useful for check what happen/ what is done or find a mods that we can like rather than see it as invisible and have no chance to know what it is.