After resuming from suspend, the Network Manager detects my WiFi signal, but eventually gives up when trying to connect to it.

These fixes did not work:

$ sudo restart network-manager

$ sudo nmcli nm sleep false

$ sudo bash -c 'echo SUSPEND_MODULES="iwlwifi" > /etc/pm/config.d/config'

Below are outputs of dmesg | tail -30 in three situations.

When laptop is turned on, WiFi is connected and working.

$ dmesg | tail -30

[    6.479195] nouveau  [     CLK][0000:01:00.0] 0f: core 270-835 MHz memory 2000 MHz 

[    6.479339] nouveau  [     CLK][0000:01:00.0] --: core 405 MHz memory 324 MHz 

[    6.511984] vga_switcheroo: enabled

[    6.512140] [TTM] Zone  kernel: Available graphics memory: 4034782 kiB

[    6.512142] [TTM] Zone   dma32: Available graphics memory: 2097152 kiB

[    6.512143] [TTM] Initializing pool allocator

[    6.512146] [TTM] Initializing DMA pool allocator

[    6.512154] nouveau  [     DRM] VRAM: 2048 MiB

[    6.512155] nouveau  [     DRM] GART: 1048576 MiB

[    6.512159] nouveau  [     DRM] TMDS table version 2.0

[    6.512160] nouveau  [     DRM] DCB version 4.0

[    6.512162] nouveau  [     DRM] DCB outp 00: 02010300 00000000

[    6.512164] nouveau  [     DRM] DCB conn 00: 00000400

[    6.513365] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).

[    6.513366] [drm] No driver support for vblank timestamp query.

[    6.513376] nouveau  [     DRM] ACPI backlight interface available, not registering our own

[    6.524228] nouveau  [     DRM] MM: using COPY for buffer copies

[    6.534906] nouveau 0000:01:00.0: No connectors reported connected with modes

[    6.534907] [drm] Cannot find any crtc or sizes - going 1024x768

[    6.565439] nouveau  [     DRM] allocated 1024x768 fb: 0x80000, bo ffff880252922800

[    6.565572] nouveau 0000:01:00.0: fb1: nouveaufb frame buffer device

[    6.565597] [drm] Initialized nouveau 1.1.2 20120801 for 0000:01:00.0 on minor 1

[    6.867191] init: plymouth-upstart-bridge main process ended, respawning

[    6.871109] init: plymouth-upstart-bridge main process ended, respawning

[   14.819661] ACPI Warning: _SB_.PCI0.PEG0.PEGP._DSM: Argument #4 type mismatch - Found [Buffer], ACPI requires [Package] (20131115/nsarguments-95)

[   14.819773] ACPI Warning: _SB_.PCI0.PEG0.PEGP._DSM: Argument #4 type mismatch - Found [Buffer], ACPI requires [Package] (20131115/nsarguments-95)

[   34.230079] audit_printk_skb: 153 callbacks suppressed

[   34.230081] type=1400 audit(1420504569.736:62): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/lib/cups/backend/cups-pdf" pid=2606 comm="apparmor_parser"

[   34.230086] type=1400 audit(1420504569.736:63): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/sbin/cupsd" pid=2606 comm="apparmor_parser"

[   34.230384] type=1400 audit(1420504569.736:64): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/sbin/cupsd" pid=2606 comm="apparmor_parser"

Right after resuming from suspend, when Network Manager is trying to connect. WiFi icon is flashing.

$ dmesg | tail -30

[ 5835.278403] wlan0: authenticated

[ 5835.281414] wlan0: associate with 20:aa:4b:71:61:ef (try 1/3)

[ 5835.389401] wlan0: associate with 20:aa:4b:71:61:ef (try 2/3)

[ 5835.429510] wlan0: associate with 20:aa:4b:71:61:ef (try 3/3)

[ 5835.463202] wlan0: association with 20:aa:4b:71:61:ef timed out

[ 5835.981063] ACPI Warning: _SB_.PCI0.PEG0.PEGP._DSM: Argument #4 type mismatch - Found [Buffer], ACPI requires [Package] (20131115/nsarguments-95)

[ 5835.981273] ACPI Warning: _SB_.PCI0.PEG0.PEGP._DSM: Argument #4 type mismatch - Found [Buffer], ACPI requires [Package] (20131115/nsarguments-95)

[ 5836.451345] wlan0: authenticate with 20:aa:4b:71:61:ef

[ 5836.455839] wlan0: send auth to 20:aa:4b:71:61:ef (try 1/3)

[ 5836.458444] wlan0: authenticated

[ 5836.460831] wlan0: associate with 20:aa:4b:71:61:ef (try 1/3)

[ 5836.568785] wlan0: associate with 20:aa:4b:71:61:ef (try 2/3)

[ 5836.571480] wlan0: RX AssocResp from 20:aa:4b:71:61:ef (capab=0x411 status=1 aid=5)

[ 5836.571487] wlan0: 20:aa:4b:71:61:ef denied association (code=1)

[ 5837.236668] wlan0: deauthenticating from 20:aa:4b:71:61:ef by local choice (reason=3)

[ 5838.717178] wlan0: authenticate with 20:aa:4b:71:61:ef

[ 5838.721191] wlan0: send auth to 20:aa:4b:71:61:ef (try 1/3)

[ 5838.723777] wlan0: authenticated

[ 5838.727683] wlan0: associate with 20:aa:4b:71:61:ef (try 1/3)

[ 5838.751269] wlan0: RX AssocResp from 20:aa:4b:71:61:ef (capab=0x411 status=0 aid=5)

[ 5838.755381] wlan0: associated

[ 5841.893920] wlan0: deauthenticated from 20:aa:4b:71:61:ef (Reason: 2)

[ 5841.901569] cfg80211: Calling CRDA to update world regulatory domain

[ 5841.906314] cfg80211: World regulatory domain updated:

[ 5841.906319] cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)

[ 5841.906323] cfg80211:   (2402000 KHz - 2472000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)

[ 5841.906326] cfg80211:   (2457000 KHz - 2482000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)

[ 5841.906328] cfg80211:   (2474000 KHz - 2494000 KHz @ 20000 KHz), (300 mBi, 2000 mBm)

[ 5841.906330] cfg80211:   (5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)

[ 5841.906333] cfg80211:   (5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)

A minute or so after the above state, it stops trying to connect. WiFi icon is empty. A notification pops up saying "Disconnected - you are now offline".

$ dmesg | tail -30

[ 5932.449208] wlan0: authenticate with 20:aa:4b:71:61:ef

[ 5932.452768] wlan0: send auth to 20:aa:4b:71:61:ef (try 1/3)

[ 5932.455454] wlan0: authenticated

[ 5932.456978] wlan0: associate with 20:aa:4b:71:61:ef (try 1/3)

[ 5932.480497] wlan0: RX AssocResp from 20:aa:4b:71:61:ef (capab=0x411 status=0 aid=5)

[ 5932.484791] wlan0: associated

[ 5935.611797] wlan0: deauthenticated from 20:aa:4b:71:61:ef (Reason: 2)

[ 5935.625479] cfg80211: Calling CRDA to update world regulatory domain

[ 5935.630150] cfg80211: World regulatory domain updated:

[ 5935.630156] cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)

[ 5935.630159] cfg80211:   (2402000 KHz - 2472000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)

[ 5935.630162] cfg80211:   (2457000 KHz - 2482000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)

[ 5935.630164] cfg80211:   (2474000 KHz - 2494000 KHz @ 20000 KHz), (300 mBi, 2000 mBm)

[ 5935.630167] cfg80211:   (5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)

[ 5935.630169] cfg80211:   (5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)

[ 5947.144676] wlan0: authenticate with 20:aa:4b:71:61:ef

[ 5947.148096] wlan0: send auth to 20:aa:4b:71:61:ef (try 1/3)

[ 5947.150573] wlan0: authenticated

[ 5947.153610] wlan0: associate with 20:aa:4b:71:61:ef (try 1/3)

[ 5947.177143] wlan0: RX AssocResp from 20:aa:4b:71:61:ef (capab=0x411 status=0 aid=5)

[ 5947.181446] wlan0: associated

[ 5950.313613] wlan0: deauthenticated from 20:aa:4b:71:61:ef (Reason: 2)

[ 5950.323551] cfg80211: Calling CRDA to update world regulatory domain

[ 5950.328210] cfg80211: World regulatory domain updated:

[ 5950.328215] cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)

[ 5950.328219] cfg80211:   (2402000 KHz - 2472000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)

[ 5950.328221] cfg80211:   (2457000 KHz - 2482000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)

[ 5950.328224] cfg80211:   (2474000 KHz - 2494000 KHz @ 20000 KHz), (300 mBi, 2000 mBm)

[ 5950.328226] cfg80211:   (5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)

[ 5950.328228] cfg80211:   (5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)