Fiber optic to wifi router help needed! [View all]

I have fiber optic internet service. Fiber into the home and optical signal converted to ethernet with a Gigapoint 803G converter. This connects via ethernet cable to a TP link AX1800 wifi router. It all works BUT the router only has one ethernet output and I want at least three and I don't want to rent the router when it's cheaper to own one.

I bought a Tenda AC1200 that has more wifi reach and the necessary ethernet outlets. It works great when connected to the one outlet on the TP Link but when I bypass the TP directly to the Gigapoint it won't connect to the internet.

I've tried configuring the Tenda without the TP as an intermediary to no avail. I want to return the TP so I don't rent it from the ISP and just use the Tenda.

Any help out there?