First, a note to self/strong suggestion to others: before screwing with anything that is likely to cause reboots, go into Applications > System > Mythbuntu Control Center > Startup behaviors and uncheck the box that starts the MythTV front end automatically at boot. Turn that back on only after all configuration agony is behind you. This is particularly important with the keyring nag (below), in which the front end started (and wiped out my access to the nag) before I could type the password, and then promptly froze the system.
The machine came with a flavor of Windows, but I immediately downloaded the latest version of Mythbuntu, burned the ISO file onto a DVD (using Brasero), and installed it on the PC, wiping away any vestige of Windows. I then rebooted and tried to configure Mythbuntu (but I'm pretty sure I will need to redo that later).
The PC comes with onboard Ethernet (one jack) but no WiFi. I will spare you the gory details (and myself the painful memories) of three failed attempts to add a USB WiFi adapter. Let's just say there were compatibility issues.
I finally ordered an Edimax EW-7811Un adapter. The Edimax is incredibly small, even more incredibly cheap (about a quarter the cost of some of the adapters I tried), and is advertised to be compatible with most Linux systems. With the power off, I plugged it into a USB slot and booted the new PC.
Oops. No network connection. Running lsusb in a terminal showed the Edimax device, but Settings > Network Connections showed two Ethernet connections and no WiFi connections. I don't think either of the "Ethernet" connections was the Edimax, but if it was, that was unhelpful, because my home LAN is secured (meaning the PC needs a password to get on it).
So I unplugged the Edimax. The Settings > Network Connections application still showed two Ethernet connections. I deleted both, not needing the onboard one and thinking the other was spurious. Big mistake. My external TV tuner is a Hauppauge WinTV-DCR, which MythTV mistakes for an HDHomeRun Prime (close enough). The first connection (which I eventually restored), eth0, was indeed the onboard Ethernet adapter. The second connection, eth1, was actually the Hauppauge tuner (even though it is coming in via a USB cable and not into an Ethernet jack). I wasted a lot of time unsuccessfully trying to install a channel lineup before it finally dawned on me that MythTV could not talk to the tuner because I had disconnected it. Fortunately, restoring the connection fixed that.
With the PC rebooted (and Settings > Network Connections showing no connections at all), I plugged in the Edimax. This time, the system immediately gave me a notification that a secured WiFi network was available. Back in Settings > Network Connections, I added a new connection, set it to WiFi, filled in my home LAN's SSID, set the security to "WPA & WPA2 Personal" and filled in the network password. Just like that, I had working WiFi.
To finish (hah! I should be so lucky) the job, I further edited the connection and made the IP address (obtained by running ifconfig in a terminal, and confirmed by looking at the status screen for my network modem) static, with mask 255.255.255.0 and gateway 192.168.1.254. I got those values by connecting my (Linux Mint) laptop to the WiFi network and running route -n in a terminal.
Next problem: on every reboot or log-in, I was nagged to type in a password to unlock the default keyring. (The correct password is my login password.) This was more than just annoying; it was fatal, as the front end would start without waiting for the password and then frequently freeze the system. Failure to unlock the keyring also seemed to keep the machine from gaining access to the WiFi network (at least I think that was the culprit). The solution I found was as follows:
- Unlock the bleeping keyring so that I could connect to WiFi.
- Install the "Passwords and Keys" application using the Ubuntu Software Center. (Seems to me this should be installed by default, even if the installation is purely a networked backend server.)
- Go to Applications > Settings > Passwords and Keys, and right-click the Default keyring entry.
- Select "Change password" and enter the current (login) password as the "old" password.
- Leave the new password blank (horrors! -- a major security hole!) and finish.
After all this, I found that I could ping outside servers by IP address but not by name. My LAN uses a (now obsolete?) 2Wire wireless DSL modem. Turns out I had to go back to Settings > Network Connections, edit the WiFi connection, and enter the gateway address (192.168.1.254, same as before) in the field for DNS servers. With that, I finally had a useable WiFi connection (which has survived a few reboots).
Sadly, there is still a lot of configuring to do.