Do I need to return old Modem?

Hello, @user_seq5pa thank you for reaching out over Xfinity Forums you've contacted the right spot to get your question answered. Yes, you will want to return the old equipment, if not returned within 30 days of activating the new Xfinity gateway you will see an unreturned equipment charge (currently $15) on a bill after 30 days. 

There a few different ways to return the old equipment as we do partner with UPS: https://www.xfinity.com/support/articles/returning-your-equipment

If you have a printer the easiest option is to visit: xfinity.com/returns , print out a label for the device you want to return, then call  1-800-PICK-UPS to schedule a pick up. The support article above on my last reply has a couple of links you can select to find the nearest certfied UPS Store or Xfinity Store with their hours of operations. If returning to a UPS store, you will need to take a box the equipment will fit in as they don't provide those and use the scan bar on the gateway to print a lable. The Xfinity Store locator also has an option to schedule an appointment to help save time when dropping the equipment off. 

Please let me know if there is anything else I can assist with.