Server stopping after left idle?

[tikitofu]

Here is the latest log. Great program by the way!

     [11:55:51] --- Started Log ---
     [11:55:51] Cuberite Jenkins gcc armhf Release (master) build id: #698
     [11:55:51] from commit id: 7960d142ca3e28e0e4550faf131398899dca90dc built at: Fri  7 Ap$
     [11:55:51] Creating new server instance...
     [11:55:51] Reading server config...
     [11:55:51] Starting server...
Info [11:55:51] Compatible clients: 1.8.x, 1.9.x, 1.10.x, 1.11.x
Info [11:55:51] Compatible protocol versions 47, 107, 108, 109, 110, 210, 315, 316
Warn [11:55:51] WebServer: The server will run in unsecured HTTP mode.
Info [11:55:51] Put a valid HTTPS certificate in file 'webadmin/httpscert.crt' and its corre$
     [11:55:51] Loaded 726 crafting recipes
     [11:55:51] Loaded 52 furnace recipes and 66 fuels
     [11:55:51] Loaded 88 brewing recipes
     [11:55:51] -- Loading Plugins --
     [11:55:51] Initialised Core v.15
     [11:55:51] Initialized ChatLog v.3
     [11:55:51] -- Loaded 2 Plugins --
     [11:55:52] Preparing spawn (world): 11.25% (45/400; 44.69 chunks / sec)
     [11:55:53] Preparing spawn (world): 31.00% (124/400; 78.14 chunks / sec)
     [11:55:54] Preparing spawn (world): 55.25% (221/400; 95.85 chunks / sec)
     [11:55:55] Preparing spawn (world): 79.75% (319/400; 96.84 chunks / sec)
     [11:55:57] Preparing spawn (world_nether): 17.75% (71/400; 70.37 chunks / sec)
     [11:55:58] Preparing spawn (world_nether): 47.50% (190/400; 117.71 chunks / sec)
     [11:55:59] Preparing spawn (world_nether): 77.25% (309/400; 117.82 chunks / sec)
     [11:56:01] Preparing spawn (world_the_end): 17.00% (68/400; 67.06 chunks / sec)
     [11:56:02] Preparing spawn (world_the_end): 46.25% (185/400; 115.50 chunks / sec)
     [11:56:03] Preparing spawn (world_the_end): 76.50% (306/400; 120.64 chunks / sec)
Warn [11:56:04] Did not find an acceptable spawnpoint. Generated a random spawnpoint positio$
Warn [11:56:04] Cannot listen on port 25565: 98 (Cannot bind IPv6 socket to port 25565: 98 ($
Err  [11:56:04] Couldn't open any ports. Aborting the server
     [11:56:04] Unloading worlds...
     [11:56:05] Disabled Core!
     [11:56:05] Cleaning up...
     [11:56:05] Shutdown successful!
     [11:56:05] --- Stopped Log ---

So I believe this happens when I try to log in at work - which is likely the cause:

Code:

Warn [11:56:04] Cannot listen on port 25565: 98 (Cannot bind IPv6 socket to port 25565: 98 ($