I'm using a 9U wall mount rack, and I also bought a rack shelf and a cyber power rack mount surge protector.
My ATT Gateway is inside my wall rack, sitting on the rack shelf I bought.
Here is the 9U Wall Rack I bought.
V7 RMWC9UV450-1N Rack Mount Wall... https://www.amazon.com/dp/B07NPG9TN9?ref=ppx_pop_mob_ap_share
There are many types of racks, I chose this one because it fit in the space I needed to mount it. So far it's been good.
This has been working great for me
https://i.imgur.com/HMtrZF4.jpg
https://smile.amazon.com/gp/product/B07NPG9TN9/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1