I haven't played Factorio since it went on Steam, but I didn't have any problems playing MP before that.
Log
P.S.: I just noticed in the log that Factorio apparently loaded the FARL and RailTanker mods twice, but I don't think that has anything to do with my problem.0.005 2016-11-09 19:57:47; Factorio 0.14.19 (build 25291, win64, steam)
0.005 Operating system: Windows 7 Service Pack 1
0.005 Program arguments: "C:\Program Files (x86)\Steam\steamapps\common\Factorio\bin\x64\Factorio.exe"
0.005 Read data path: C:/Program Files (x86)/Steam/steamapps/common/Factorio/data
0.005 Write data path: C:/Users/boule's travel comp/AppData/Roaming/Factorio
0.005 Binaries path: C:/Program Files (x86)/Steam/steamapps/common/Factorio/bin
0.041 System info: [CPU: Intel(R) Core(TM) i5-3320M CPU @ 2.60GHz, 4 cores, RAM: 3791MB]
0.041 Display options: [FullScreen: 1] [VSync: 0] [UIScale: 100%] [MultiSampling: OFF] [Screen: 255]
0.043 Available display adapters: 1
0.043 [0]: \\.\DISPLAY1 - Intel(R) HD Graphics 4000 {0x05, [0,0], 1366x768, 32bit, 50Hz}
0.043 Create display on adapter 0. Size 1280x720 at position [33, 6].
0.126 Initialised Direct3D:[0] Intel(R) HD Graphics 4000; driver: igdumdim64.dll 9.18.10.3359
0.145 Video memory size (dedicated video/dedicated system/shared system/available): 64/0/1632/1692 MB
0.257 DSound: Starting _dsound_update thread
0.257 DSound: Enter _dsound_update; tid=6336
0.257 Device reset internal.
0.262 Desktop composition is active.
0.264 Graphics options: [Graphics quality: low] [Video memory usage: high] [Light scale: 25%] [DXT: false]
0.426 Loading mod core 0.0.0 (data.lua)
0.438 Loading mod base 0.14.19 (data.lua)
0.563 Loading mod FARL 0.7.0 (data.lua)
0.630 Loading mod Explosive Termites 1.1.9 (data.lua)
0.701 Loading mod RailTanker 1.4.0 (data.lua)
0.783 Loading mod FARL 0.7.0 (data-updates.lua)
0.871 Loading mod rso-mod 2.2.7 (data-updates.lua)
0.942 Loading mod Omnibarrels 1.1.3 (data-updates.lua)
1.028 Loading mod FARL 0.7.0 (data-final-fixes.lua)
1.095 Loading mod RailTanker 1.4.0 (data-final-fixes.lua)
1.169 Checksum for core: 1291735968
1.169 Checksum for mod base: 786624017
1.169 Checksum for mod FARL: 1016738590
1.169 Checksum for mod rso-mod: 1874398137
1.169 Checksum for mod Explosive Termites: 554546608
1.169 Checksum for mod Omnibarrels: 2132636919
1.169 Checksum for mod RailTanker: 1260574978
1.590 Info PlayerData.cpp:55: Local player-data.json available, timestamp 1478717863
1.590 Info PlayerData.cpp:60: Cloud player-data.json available, timestamp 1478712783
1.753 Initial atlas bitmap size is 8192
1.754 Created atlas bitmap 8192x5296
1.754 Created atlas bitmap 4096x912
1.755 Created atlas bitmap 4096x1052
14.122 Sprites loaded
14.122 Convert atlas 4096x912 to: trilinear-filtering
14.190 Convert atlas 4096x1052 to: mipmap
14.752 Loading sounds...
16.549 Custom inputs active: 0
16.601 Factorio initialised
102.202 Info ServerSynchronizer.cpp:27: nextHeartbeatSequenceNumber(0) initialized Synchronizer nextTickClosureTick(0).
102.202 Info ServerMultiplayerManager.cpp:658: mapTick(-1) changing state from(Ready) to(PreparedToHostGame)
102.203 Info ServerMultiplayerManager.cpp:658: mapTick(-1) changing state from(PreparedToHostGame) to(CreatingGame)
102.203 Info Scenario.cpp:152: Map version 0.14.19-0
102.269 Checksum for script C:/Users/boule's travel comp/AppData/Roaming/Factorio/temp/currently-playing/control.lua: 1057114497
102.280 Checksum for script __FARL__/control.lua: 1521588408
102.292 Checksum for script __rso-mod__/control.lua: 863068844
102.295 Checksum for script __Explosive Termites__/control.lua: 2275287822
102.297 Checksum for script __RailTanker__/control.lua: 2344758156
102.300 Info UDPSocket.cpp:27: Opening socket at (0.0.0.0:34197)
102.302 Hosting game at 0.0.0.0:34197
102.302 Info HttpSharedState.cpp:44: Downloading https://auth.factorio.com/generate-server-padlock
102.799 Info HttpSharedState.cpp:111: Status code: 200
102.799 Info AuthServerConnector.cpp:106: Obtained serverPadlock for serverHash (wWtnbcmcZDJ2qYvaamQ1tDqTFRgLWPGY) from the auth server.
102.799 Info ServerMultiplayerManager.cpp:658: mapTick(0) changing state from(CreatingGame) to(InGame)
102.799 Info ServerRouter.cpp:604: Asking pingpong servers (pingpong1.factorio.com:34197, pingpong2.factorio.com:34197) for own address
102.800 Info UDPSocket.cpp:39: Opening socket for broadcast
102.803 Info GameActionHandler.cpp:2556: MapTick(0) processed PlayerJoinGame peerID(0) playerIndex(0) mode(create)
102.924 Warning ServerRouter.cpp:492: Received own adddress message reply with conflicting address (got 91.176.235.13:52849, expected 91.176.235.13:52850)
102.924 Warning ServerMultiplayerManager.cpp:551: Determining own address has failed. Best guess: 91.176.235.13:52850
103.953 Info ServerMultiplayerManager.cpp:587: Matching server connection resumed
0.005 Operating system: Windows 7 Service Pack 1
0.005 Program arguments: "C:\Program Files (x86)\Steam\steamapps\common\Factorio\bin\x64\Factorio.exe"
0.005 Read data path: C:/Program Files (x86)/Steam/steamapps/common/Factorio/data
0.005 Write data path: C:/Users/boule's travel comp/AppData/Roaming/Factorio
0.005 Binaries path: C:/Program Files (x86)/Steam/steamapps/common/Factorio/bin
0.041 System info: [CPU: Intel(R) Core(TM) i5-3320M CPU @ 2.60GHz, 4 cores, RAM: 3791MB]
0.041 Display options: [FullScreen: 1] [VSync: 0] [UIScale: 100%] [MultiSampling: OFF] [Screen: 255]
0.043 Available display adapters: 1
0.043 [0]: \\.\DISPLAY1 - Intel(R) HD Graphics 4000 {0x05, [0,0], 1366x768, 32bit, 50Hz}
0.043 Create display on adapter 0. Size 1280x720 at position [33, 6].
0.126 Initialised Direct3D:[0] Intel(R) HD Graphics 4000; driver: igdumdim64.dll 9.18.10.3359
0.145 Video memory size (dedicated video/dedicated system/shared system/available): 64/0/1632/1692 MB
0.257 DSound: Starting _dsound_update thread
0.257 DSound: Enter _dsound_update; tid=6336
0.257 Device reset internal.
0.262 Desktop composition is active.
0.264 Graphics options: [Graphics quality: low] [Video memory usage: high] [Light scale: 25%] [DXT: false]
0.426 Loading mod core 0.0.0 (data.lua)
0.438 Loading mod base 0.14.19 (data.lua)
0.563 Loading mod FARL 0.7.0 (data.lua)
0.630 Loading mod Explosive Termites 1.1.9 (data.lua)
0.701 Loading mod RailTanker 1.4.0 (data.lua)
0.783 Loading mod FARL 0.7.0 (data-updates.lua)
0.871 Loading mod rso-mod 2.2.7 (data-updates.lua)
0.942 Loading mod Omnibarrels 1.1.3 (data-updates.lua)
1.028 Loading mod FARL 0.7.0 (data-final-fixes.lua)
1.095 Loading mod RailTanker 1.4.0 (data-final-fixes.lua)
1.169 Checksum for core: 1291735968
1.169 Checksum for mod base: 786624017
1.169 Checksum for mod FARL: 1016738590
1.169 Checksum for mod rso-mod: 1874398137
1.169 Checksum for mod Explosive Termites: 554546608
1.169 Checksum for mod Omnibarrels: 2132636919
1.169 Checksum for mod RailTanker: 1260574978
1.590 Info PlayerData.cpp:55: Local player-data.json available, timestamp 1478717863
1.590 Info PlayerData.cpp:60: Cloud player-data.json available, timestamp 1478712783
1.753 Initial atlas bitmap size is 8192
1.754 Created atlas bitmap 8192x5296
1.754 Created atlas bitmap 4096x912
1.755 Created atlas bitmap 4096x1052
14.122 Sprites loaded
14.122 Convert atlas 4096x912 to: trilinear-filtering
14.190 Convert atlas 4096x1052 to: mipmap
14.752 Loading sounds...
16.549 Custom inputs active: 0
16.601 Factorio initialised
102.202 Info ServerSynchronizer.cpp:27: nextHeartbeatSequenceNumber(0) initialized Synchronizer nextTickClosureTick(0).
102.202 Info ServerMultiplayerManager.cpp:658: mapTick(-1) changing state from(Ready) to(PreparedToHostGame)
102.203 Info ServerMultiplayerManager.cpp:658: mapTick(-1) changing state from(PreparedToHostGame) to(CreatingGame)
102.203 Info Scenario.cpp:152: Map version 0.14.19-0
102.269 Checksum for script C:/Users/boule's travel comp/AppData/Roaming/Factorio/temp/currently-playing/control.lua: 1057114497
102.280 Checksum for script __FARL__/control.lua: 1521588408
102.292 Checksum for script __rso-mod__/control.lua: 863068844
102.295 Checksum for script __Explosive Termites__/control.lua: 2275287822
102.297 Checksum for script __RailTanker__/control.lua: 2344758156
102.300 Info UDPSocket.cpp:27: Opening socket at (0.0.0.0:34197)
102.302 Hosting game at 0.0.0.0:34197
102.302 Info HttpSharedState.cpp:44: Downloading https://auth.factorio.com/generate-server-padlock
102.799 Info HttpSharedState.cpp:111: Status code: 200
102.799 Info AuthServerConnector.cpp:106: Obtained serverPadlock for serverHash (wWtnbcmcZDJ2qYvaamQ1tDqTFRgLWPGY) from the auth server.
102.799 Info ServerMultiplayerManager.cpp:658: mapTick(0) changing state from(CreatingGame) to(InGame)
102.799 Info ServerRouter.cpp:604: Asking pingpong servers (pingpong1.factorio.com:34197, pingpong2.factorio.com:34197) for own address
102.800 Info UDPSocket.cpp:39: Opening socket for broadcast
102.803 Info GameActionHandler.cpp:2556: MapTick(0) processed PlayerJoinGame peerID(0) playerIndex(0) mode(create)
102.924 Warning ServerRouter.cpp:492: Received own adddress message reply with conflicting address (got 91.176.235.13:52849, expected 91.176.235.13:52850)
102.924 Warning ServerMultiplayerManager.cpp:551: Determining own address has failed. Best guess: 91.176.235.13:52850
103.953 Info ServerMultiplayerManager.cpp:587: Matching server connection resumed