@Uro
You accuse me of trying to raise my ticket profile by linking unrelated issues which I deny
I related your issue since it looked like the root cause of the problem I am facing (memory leak => server not found in the server list)
Btw it is someone else who send me the link to your post because he also thought it was related to my issue.
If you don' want to link your issue to mine, fine with me but that won't help solve our issues which do seem related

Some players (not more than 5) joined the server today and played about 1 hour before all of them lost connection with server at the same time.

I noticed 2 new parameters in the server JSON config file and added them to server config, then restarted.
"a2sQueryEnabled": true,
"steamQueryPort": 17777

Yesterday I patched the server to 0.9.5.61 version, emptied the .save folder, changed the mission to {1AEE808E7689FE54}Missions/23_Campaign_NWCoast.conf, restarted the server and launched the mission by connecting to the server then disconnected.

Not duplicate, just read the title of this ticket. And yeah I searched before for existing tickets and didn't find yours because at that moment I wasn't aware of this memory leak problem (I discovered it afterwards).

I changed maxFPS from 120 to 60 and I notice the same behaviour : over less than 24 hours period the memory usage increases (eg from 5 GB to 12 GB as I write) although only one player connected to the game at the beginning of this period and no other players connected afterwards.

I noticed for the second time that, as time passes by (after one or two days), the reforger dedicated server process ends up using almost all memory (94%, check attachment) and ssh session becomes slow and later even impossible (ssh requests timeout). I have to restart server from the web management console.

only bohemia can do that
when you click "edit task" on the right panel you get a message "you do not have permissions etc"

Good news
I was lucky to find an old game save (just before I started dealing with the Harcourt and rescue captive quests) and I was able to complete the following quest tasks with the following method: as soon as Keystone gives you a mission go straight there, do nothing else

• rescue the captive (this one worked before as well)
• give wallet to garagist (this one was blocked before, nothing happened after executing 'give item' action)
• steal top secret files from Harcourt (this one worked before as well)
• give top secret files to Keystone (this one worked before as well)
• get rebreather from Losi gendarme base (this was blocked before when I bought the rebreather from the black market)
• dive down and gather the Intel (this time it worked perfectly when executing action)

same problem, only BIS DLC used (Contact DLC not used), no mods:

there is another way to make infinite money

change priority from 'normal' to 'immediate' as this is a 'game breaking' issue (campaign cannot end)
also upload your save file (eg C:\Users\<windows user>\Documents\Arma 3 - Other Profiles\<player name>\Saved\a3\Missions_F_Oldman\Campaign\Missions\Oldman.Tanoa\save.Arma3Save)

duplicate of https://feedback.bistudio.com/T150549
change state from 'new' to to 'duplicated'

duplicate of https://feedback.bistudio.com/T150549
change state from 'new' to to 'duplicated'

duplicate of https://feedback.bistudio.com/T150485
you should upload your game save and add a comment on that task

there is a similar type of issue with another quest 'Recover photos from planed crashed at the bottom of the sea': https://feedback.bistudio.com/T152023

encountered same problem
if you have a rifle, a possible workaround is to go to 'sit on your ass' stance and then you can move out of the building

you can create your own dashboard and create panels in you dashboard (check mine https://feedback.bistudio.com/dashboard/view/123/)
and these panels can be created from saved queries and in those saved queries you can filter by 'created by <username>' so you can keep track of all your reported issues

duplicate of https://feedback.bistudio.com/T150627
change state to 'duplicated'

duplicate of https://feedback.bistudio.com/T150594
change status to 'duplicate'

Same problem
Started playing Old Man on December 11th