[RyDeR`]

Code can be optimized. Just return if it's find if not just INVALID_PLAYER_ID also use !IsPlayerNPC(playerid) to skip bot checks.

pawn Code:

stock GetPlayerIDFromIP(ip[])
{
    new
        pIp[16]
    ;
    for(new i; i != MAX_PLAYERS; ++i)
    {
        if(IsPlayerConnected(i) && !IsPlayerNPC(i))
        {
            GetPlayerIP(i, pIp, sizeof(pIp));
            
            if(!strcmp(ip, pIp, true)) return i;
        }
    }
    return INVALID_PLAYER_ID;
}

Hope you don't mind. Just trying to help.