Edited to the original message from TheMickster at How to connect an apple tv to hotel wifi
YES - you can definitely do this easily. It will take about 15 minutes.
You need to know:
1. What is the MAC address of the Apple TV that you own. Though pronounced the same as Mac, it refers to an industry standard of identifying a specific device. It stands for Media Access Control.
2. Who is the provider that the hotel is using - you can get this at the hotel.
TO FIND THE MAC ADDRESS:
This can be done before you pack your Apple TV and leave your house
1. Connect your Apple TV to the TV... turn both on... blah blah blah... Apple TV is displayed on the TV
2. Go to Settings > General > About
3. If you are still at home, then you will be connected to Wi-Fi. If you are at the hotel, then turn on your phone's W-Fi hotspot and connect the Apple TV to the phone wireless network (not to the hotel Wi-Fi).
3. The MAC address is labeled as "Wi-Fi Address" in this situation (SEE PHOTO BELOW). It will be a set of 6 pairs of alphanumeric characters, each pair separated by a colon. For example... 00:11:22:cc:bb:aa (they'll look more random than this, but I didn't want to take a chance on posting someone's real MAC address)
4. Write down that address.
THE HOTEL'S SERVICE PROVIDER
The service provider's information will typically be right in the hotel room because there is no reason for hotel staff to have to troubleshoot this stuff for us. If not, call the front desk and ask for the number of the Wi-Fi provider - let them know you have technical issues and need to talk to the provider.
1. Call the support number and follow their prompts to get to a support agent.
2. Say, "Hello! I have an Apple TV, and I understand I can connect to your service by registering the MAC address with your service."
3. They will ask you several questions to verify that you are staying at one of the hotels they service.
4. Follow their instructions for registering the MAC address
5. On your Apple TV, go to Settings > General > Network > Wi-Fi, and select the hotel's Wi-Fi.
6. Voila! CONNECTED and Ready to Go!!!
What I have found that it works to connect the Apple TV to the Internet, so you can watch movies on Apple, Netflix, etc. But it did not work when I wanted to connect my Macbook to the TV via Apple TV.