The Sutro hub cannot connect to 5 GHz. Make sure that the WiFi that you're trying to connect to is 2.4 GHz.
After initially connecting to the Sutro network, sometimes your phone will disconnect the Sutro network because there is no connectivity, and it will auto-switch to your home WiFi or cell data. Try the following, and then reset your huband connect to the Sutro network again.
Change settings in the phone to not auto-switch to cellular
iPhone - This is labeled as WiFi Assist. Go into the Cellular settings on your iPhone. Scroll to the bottom and make sure WiFi Assist is turned off.
Android - This is labeled as Smart/Intelligent WiFi.
Go into the Connections settings and select WiFi. Click on the 3 menu dots on the top right-hand side, then click Advanced Settings. Make sure all Smart/Intelligent WiFi settings are turned off.
Android Users: When connecting to the Sutro network, you may see a notification that says to tap for options. Android will inform you that the Sutro network has limited or no connectivity. Click stay connected.
"The network does not look like a Sutro hub"
If you get the error above, it just means that you switched back to the app before the hub was able to fully connect. After connecting to the Sutro network, wait 15 seconds for the network to fully establish a connection, and then go back into the Sutro application.