To connect your PIXMA TS6120 to your wireless network, please follow these steps:
1. Press the HOME button on your PIXMA TS6120.
2. Select Setup on the Home screen (it is the gear icon at the bottom of the LCD screen).
3. Select Settings.
4. Select Device Settings.
5. Select LAN settings.
6. Select Wireless LAN.
7. Select Wireless LAN setup.
8. Select Manual connect.
9. Select your wireless network name.
10. Enter your wireless network password.
11. Select OK when "Connected to the wireless router." appears.
Your PIXMA TS6120 is now connected to your wireless network.
Thanks for looking at my issue.
Unfortunately it isn't that simple.
I think it has to do with the frequency band from Tmobile. I have 2.4GH and 5GH. The printer supports 2.4 GH.
I have to request to split the band, or I have to get a cable.