There seems to be a bug in the MPWP firmware that I've been trying to address with tech support, but I figure I'll post here too in case anybody's tearing their hair out. The bug is, I can connect to my home wifi network (for internet pass-through, and network-wide access of the MPWP) ONLY on initial product setup, i.e. the out-of-box experience. After a powercycle, the MPWP won't reconnect to the network, and trying to reset the network settings doesn't fix anything. Fully resetting the drive does let me connect again, but only once, and only during the initial out of box setup.
I believe I've isolated the problem to an ampersand (&) in my home wifi password. Here's the email I just sent to try and open a bug report with WD support:
I believe this case needs to be reopened. I have received the replacement unit, it functions as expected, but the problem persists. I have isolated the root cause, which I believe to be a software bug in handling the text of the wifi password for remembered networks. Specifically, my network password has an ampersand (&) in it. Further details to recreate the problem.
Initial condition: Normal network name (all lower case chars) and password (lower case chars, numerals, and one &). Same SSID on both 5GHz and 2.4GHz bands.
1) I open the new package and proceed to turn the device on. I connect to its 5GHz wifi network, and go through the setup flow.
2) Upon getting to network configuration for connecting to internet, I input my network name (mynet) and password (my&pass11) (approximately) The device successfully connects to the internet, which I verify by visiting webpages while connected to the device (MyPassport 5GHz) SSID.
3) Power cycle device.
4) Verify the device hasn't connected to 'mynet' by trying to visit http://mypassport/
5) Verify the device hasn't connected to 'mynet' by connecting my computer to 'MyPassport 5GHz' and looking at the wifi tab.
6) Try to connect the device manually to 'mynet' by selecting 'mynet' on the wifi tab. The first time I get to (6), the MPWP won't connect, showing an error like "Couldn't connect, be sure you're in range". On subsequent attempts, it'll prompt for a new password, assuming that's the problem. When I put in the correct password (my&pass11) it fails with "Password is incorrect" (the password is correct, assuredly.)
7) Reset to factory defaults. Successfully reproduce 1-6.
8) At this point, the MPWP installed a firmware update. I'm not sure why - it must have downloaded during one of my successful connections on step (2). It's now on firmware v1.03.04
9) I log into my home router and change the wifi password on both 2.4 and 5GHz bands to 'mypass11', removing the ampersand.
10) I connect to 'MyPassport 5GHz' and reconfigure the 'mynet' wifi network with the new password.
11) At this point, the device works reliably through power cycles, reconnecting to 'mynet' within a few moments of reboot. I can access it at http://mypassport/ while connected directly to 'mynet' on my computer, and I can access the internet while connected to 'MyPassport 5GHz'. Tried this with a few power cycles, just for sanity.
12) Switch the network password back to the original on both bands (my&pass11)
13) Verifiy steps 3-7, reliably.
I conclude that there's a bug in handling how special characters in the wifi password outside of the initial setup flow. It seems likely that it's something to do with how they're written to disk, but if that's true, I'm not sure why I'm unable to manually reconnect with any success in step (6).
Please file this as a bug, and if possible, I'd quite like to know when it gets fixed.