Roku LT vs. Roku 3: does it matter?

@user86

My Internet:
FIOS 50/50 speed. My gateway router/modem is connected by a cable (not the WAN)

I’m thinking about replacing my router and am looking at the TP-Link WDR3600, the one you recommend.

However, my current “router” also contains the modem.
So, I have to buy a modem also ?? If yes, which one do you recommend.

Thanks

Chas