How to set up Pace 5031NV internet only with TD-W8980 behind it?

I recently switched from ATT ADSL to Uverse internet, and I don't have everything set up back the way I want it.

I had a test with a different DSL service on ATT's infrastructure in between, and had the TP-Link modem-router (modem disabled, that was the DHCP server) behind a (different) Pace, my router's IP in the same network which is different from the ATT router.

My router has 2 USB ports and is dual band. I had an old HP network printer working (also in the same IP network) and was able to use a drive dock and a portable drive in the USB ports, and access all those both wired and wireless. I don't know if I had it set up the "right" way (i.e. most secure), but it worked. Also connected to mine was a Directv broadband adapter.

Right now, the Directv adapter and my laptop are attached to the ATT Pace. I can access wifi with my tablet on the Pace. I have to use the USB connection to print since I need to get into the printer (and my router) and change the IP, or reset them.

Can someone advise how to set up the ATT Pace 5031NV with the TD-W8980 securely behind it in order to use it this way (if you don't know the specifics of the TD-W8980 then tell me what to look for and change, generally):

Laptop is mostly used wired (ethernet), but sometimes wireless. Cloud backup (document and a lot of photo/media files, which is mostly caught up at this point)

Directv broadband adapter is for on-demand (not a lot, but sometimes)

External hard drive dock and portable drive for local backup/storage (both USB, mapped drives through my router) mostly ethernet, sometimes wireless

Printer mostly ethernet, sometimes wireless