Nah, not confusing at all.
You have three cable modems, of which it looks like one (the silver SMC) is actually in use. All three are being fed from the three way splitter. I would guess the two, smaller black cable modems were for tenants that wanted their own connections, and paid for them, but have now been abandoned. Cable modem in the closet, plugged into the Ethernet patch panel feeding the apartment and the tenant has their own router...simple.
Plug a laptop into those smaller cable modems (with a good security suite installed on the laptop!) and see if you get an IP address. If you don't, they're probably cut off from service. Also check the lights... If you do get an IP address and can connect to the internet, you now have more bandwidth, but will have to work it into the router in one of the "NA" ports...if the router can handle it.
In reality, and from what I see, you have two internet connections going into one router, which then feeds two Ethernet switches. Like I previously stated, test your speeds while plugged DIRECTLY into the cable modem, then the DSL modem/router. Eliminate that questionable router from the equation.
Oh, and the smart jack was probably installed for a T1/fractional T1 some time ago...looks to be abandoned now.
edit: Saving the jpg killed some of the text I added. The cable splitter is above the SMC cable modem.