How to properly increase the speed of my Performance Internet Service by up to 25%?

Probably a dumb question, but I'll ask it anyway & hope for clarification..........

I just got a notice in my latest bill to go to:  comcast.com/powercycle   to upgrade the speed of my Performance Internet Service by up to 25%.

When I go there, I am instructed to do the below with my modem & router, depending on which of the 2 services I have.

Problem is, I have Xfinity Internet& TV, but no voice, and I just have a single "Gateway" unit (Arris TG862) vs both a modem & a router.

Can anyone tell me the proper sequence for this scenario?

Thanks in advance!

Comcast Instructions from Website:

Introduction

You can fix certain modem issues by resetting or power cycling your cable modem or your XFINITY Internet & Voice modem.

Cable Modem Users

Reset your cable modem by pressing and holding down the reset button, located on the front or back of your modem, for five seconds. If there’s no reset button, then power cycle your modem.

To power cycle your modem:

1. Shut down your computer.
2. Unplug the cable modem from the electrical outlet.
3. Wait 10 seconds, then plug the cable modem back into the electrical outlet.
4. Unplug your router from the electrical outlet.
5. Plug your router back in.
6. Wait 30 seconds, then turn your computer back on.

XFINITY Internet & Voice Modem Users

1. Shut down your computer
2. Find the reset button on the back of the unit.
3. Use a pen or any pointed, non-metallic object to press the reset button until you see the lights on the front of the unit go off.
4. Release the reset button and wait for the unit to cycle up (this may take up to five minutes).
5. Unplug your router from the electrical outlet.
6. Plug your router back in.
7. Wait 30 seconds, then turn your computer back on.