Wireless *intermittently* fails to connect upon boot

Question

Hi folks,
First post! After a few days of grinding away, I've got my first Arch Linux installation up and running alongside a Windows 7 partition. As a relatively inexperienced Linux user, it's been challenging at times, but I'm very happy with the new setup and I've resolved most problems encountered thus far.
However, I've run into an irksome problem that I haven't yet been able to solve:
Most of the time when I boot into Arch Linux, my wireless connection starts automatically via netctl. I can open up Chromium and browse straight away.
However, perhaps every 2-3 boots, I start an Arch Linux session where I find that my wireless has not connected. I'll open up Chromium and receive errors, then I'll open up a terminal and find that 'iwconfig' isn't showing any active wireless connection.
I've done my share of Googling on this, and browsed the Arch wiki to try and find an answer, but many of the solutions that I have found relate to the problem of a wireless connection refusing to connect at all. This doesn't apply to my case, so I thought I'd put this out to the panel of resident experts here!
Here's my iwconfig when I boot into a 'good' session with working wireless:
eno1      no wireless extensions.
wlp4s0    IEEE 802.11bgn  ESSID:"ZyXEL7850rtg" 
          Mode:Managed  Frequency:2.472 GHz  Access Point: 50:67:F0:E8:4E:00   
          Bit Rate=150 Mb/s   Tx-Power=20 dBm   
          Retry  long limit:7   RTS thr=2347 B   Fragment thr:off
          Power Management:off
          Link Quality=70/70  Signal level=-35 dBm 
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:1   Missed beacon:0
lo        no wireless extensions.
Here's my iwconfig when I boot into a 'bad' session with no wireless:
eno1      no wireless extensions.
wlp4s0    IEEE 802.11bgn  ESSID:off/any 
          Mode:Managed  Access Point: Not-Associated   Tx-Power=20 dBm   
          Retry  long limit:7   RTS thr=2347 B   Fragment thr:off
          Power Management:off
lo        no wireless extensions.
Other relevant info:
- I have recently migrated to netctl from netcfg, as instructed in the Arch wiki. I was hoping that this would resolve my problem, as the exact same issue previously occurred for me on netcfg. Unfortunately, the problem remains intact.
- I see no such issues on my Windows 7 partition (the wireless connection always works upon boot), so it would appear that hardware issues can be ruled out.
- When wireless fails to start upon boot, I can still connect by entering 'sudo wifi-menu wlp4s0' and specifying the desired connection manually. So I don't have to reboot to get my connection working, but nonetheless, this is a nuisance.
I'm not sure what other data (logs etc.) might be useful in diagnosing this issue, but I'd be grateful for any pointers.
Thanks in advance for any assistance or newbie-bashing rendered!

Answer 1

Thanks for the suggestion Aton. I reproduced the problem, and then sifted through journalctl to see what I could find.
I dug up the following lines of interest:
Apr 15 18:31:02 kevin-pc network[297]: Starting network profile 'wlp4s0-ZyXEL7850rtg'...
Apr 15 18:31:15 kevin-pc dhcpcd[487]: timed out
Apr 15 18:31:15 kevin-pc network[297]: DHCP IP lease attempt failed on interface 'wlp4s0'
Apr 15 18:31:15 kevin-pc kernel: wlp4s0: deauthenticating from 50:67:f0:e8:4e:00 by local choice (reason=3)
Apr 15 18:31:15 kevin-pc network[297]: Failed to bring the network up for profile 'wlp4s0-ZyXEL7850rtg'
Apr 15 18:31:15 kevin-pc systemd[1]: netctl@wlp4s0\x2dZyXEL7850rtg.service: main process exited, code=exited, status=1/FAILURE
Apr 15 18:31:15 kevin-pc systemd[1]: Failed to start Automatically generated profile by wifi-menu.
Apr 15 18:31:15 kevin-pc systemd[1]: Unit netctl@wlp4s0\x2dZyXEL7850rtg.service entered failed state
I have no idea what to make of this, but it's good to get some new information.
I'm going to Google around a bit with some of these error messages. In the meantime, I open the floor to suggestions if anyone discerns anything obvious in the output above...