Unable to return Comcast router

I have recently cancelled my Comcast internet service as I have moved to an already-connected home. However, I have found the process of returning my router to be a bit painful. I attempted to return it at my local Xfinity store, but since my new residence was far away from where my original service was, they would not let me return it there. I then tried (on multiple occasions) to print the return label so I could use UPS, but I was unable to do so. To clarify, I:

• Went to https://customer.xfinity.com/devices/returns and found my router
• Filled out initial details until getting to the "Print your return label" screen
• Get shown this image:

This screen has appeared for several days in a row. I tried calling support and either talked to a bot (who couldn't help me), or was put on hold for a long time before the call just hung up out of nowhere. I really would like to deal with this as soon as possible as I don't want to be charged late fees and will also be leaving on a lengthy trip soon and so would not be able to return it for several weeks.

I would really appreciate any help, thanks!

Edit: I was finally able to print the shipping label, but the return address is incorrect. Since I have changed addresses, I no longer want the return address to be my previous residence, but rather my new one. I'm not sure how I can update this. Thanks!