What if 2 Wi-Fi networks?

Tablo’s quick start guide refers to “your home’s Wi-Fi network” but our router came with two: 2.4 GHz and 5 GHz. Do all the devices involved (in our case iPhone, Android phone, Roku device, Roku TV, and of course the Tablo) need to be on the same network? Until now I have been keeping the Roku TV on 5 because it’s closest to the router and everything else on 2.4 for better range, but all the devices can see both networks just fine.

Unless your wireless router is set to utilize isolation mode, which prevents network devices from communicating with each other, devices connecting via 2.4GHz, and others connecting at 5GHz are in the same local area network.
They’re just using a different method to connect to that local area network.
You can also connect devices via network cables, and those too will be on the same local area network.

As above, as long as AP isolate mode isn’t turned on, all WiFi devices connected to both the 2.4 GHz and 5 GHz networks should be able to access the Tablo.

Are you connecting your Tablo to the router via an Ethernet cable? Or are you connecting via WiFi?

Connected via Wi-Fi.

What is the make and model of your router?

I would recommend you connect the Tablo to the 5 GHz network especially if your router is Wireless AC. If it’s Wireless N, you can experiment which network works better for the Tablo to be connected to.

They are all the same network regardless of the frequency band. 5GHz is fast but lacks the range (distance) of 2.4GHz.