@hlee Welcome to TPG Community.
I'm sorry to hear that the wifi is not working. Does it mean that your internet as a whole is not working or can you connect to the internet when your device is connected to the modem through ethernet cable?
The contents of the article below may help.
I tried to look for your particular account using the username, e-mail address and e-mail address provided. I would like to look into this further. Can you PM your account details to any MOD here?