Your extDB3 is working fine. The problem has to be found in your life_server mod. Looking through your .rpt log, I can read, that your containers (con_a, con_b, ...) cannot be found. Usually this means that there are no containers in your mission.sqm file. Please make sure you got a correct mission file loaded.
You could also try to change your startup parameters. You're running @life_server and @extDB3 as a -mod. Try to run them as a -servermod.
Since it can't find your containers, you could also try to give those containers as a parameter to the script. This would mean, that you'd have to change the line
private _containerss = [con_b,con_d,con_a,con_e,con_h];
ans instead use something like
private _containerss = _this;
Using the magic variable _this means you'd have to change the script that calls the fetchGangCont script. Instead of
call TON_fnc_fetchGangCont;
you would need
[con_b, con_d, con_a, con_e, con_h] call TON_fnc_fetchGangCont;
This should do the trick.