SOLUTION
Although Mines wired and wireless networks appear to be open (not password protected), to use them you must first "register" your computer with the network. To do that, you must first create your official Mines account. (You will receive information about that before coming to Mines.) Thus, while the Mines networks require no password, they are not open to everyone -- with one minor exception noted below.
Normally, when you first connect to a Mines network and open a web browser, you will be redirected to a registration page. (If you are connecting wirelessly, choose the network called "Mines" to start.) Complete the form using your campus username and password. Then wait 10 minutes and reboot your system. That computer is now permanently registered on that network.
Remember to repeat the process for each campus network you wish to use. The wired network requires one registration and the Mines wireless network requires another. Also, remember to complete registration for each different computer, tablet, or phone with which you access the network. One registration connects one machine to one Mines network only.
The network called "Mines-Guest" is used for visitors taking short courses and other temporary access needs. Anyone may access this network for a finite amount of time (generally 24 hours) by accepting the End-User License Agreement. To regain access to the Mines-Guest network, please accept the End-User License Agreement.
The network called "eduroam" (all lower case) requires a bit more setup to use, but is encrypted by default and can be accessed at any participating university who also has an eduroam network available. We recommend it highly. Here's how to connect your device to the eduroam network.
NOTES
Sometimes a web browser is not redirected to the proper network-registration page the first time you access a Mines network. In that case, just point your new device's web browser at https://netreg.mines.edu and complete the form. Once you have registered, wait about 10 minutes and reboot your device. When you have registered once for that network, you will not need to register again and doing so may cause unpredictable effects on your network service.
As always, if you experience difficulty registering your device for network access, seek help from a student consultant in the Computer Commons, CT 156. Or submit a Mines Help Center support request at https://helpdesk.mines.edu.