I spent a stupid amount of time after getting this for $30 at a thrift store new-in-box, that the Advanced Tomato and DD-WRT firmware that supports R7000 does NOT support R7000P with the CenturyLink ONT as the SOC drivers will not allow Vlans that are numbered anything other than 1-12.
Despite many hours trying to get anything other than the default firmware to go I had no luck and ultimately discovered (at least as of this writing 2/2021) that was not an option for this router. Special thanks for Kevin Woley's blog post that had most of the answers that I needed to do for this.
In order to begin the installation, the first step is to boot up the router with the ONT that was plugged into your (probably Technicolor/Zyxel C3000Z) CenturyLink router. Only one port of your ONT will be provisioned to allow traffic on Vlan 201. If this is your first time booting the router, you will need to establish a password and secret questions/answers. Once you establish the username/questions and everything boots up, you will have a menu like this:
Select Advanced Internet Setup and check yes/PPPoE on "Does your internet connection require a login?" Call CenturyLink repair if you do not have this credential. Their main support number cannot get this for you, but their GPON fiber repair folks in Boise can, and their number is
Enter VLAN/Bridge settings and enable this feature, it will default to VLAN 10, but we will change this in the next menu.
Ensure that the VLAN is 201 which is what the CenturyLink ONT which is upstream uses to tag the traffic.
Enable VLAN Tagging Group
Set Wireless Settings to your liking; this is the easy part.
Ensure that you disable MU-MIMO in the Advanced Wireless Setup Menu - my speeds and connection were constantly crashing before I disabled this setting.
Let your speed tests rip! These will depend on the MIMO attributes of your workstation, obstructions between you and the access point, and the noise floor of 5GHZ locally - but you should expect at least several hundred megabit up and down - you typically will get better download speeds.
I know this is pretty straightforward, but feel free to reach out in the comments section below if you are having any issues and I will do my best to help you diagnose and troubleshoot.