NetWork Extend with router AC2600 Nighthawk

My question is am I using my AC2600 router in the best way possible, given recent network changes in my house?

Recently I upgraded my home router from a LinkSys to the NetGear AC2600, which has nice range on it.  This however still did not increase my network speed much, so I contacted my internet provider, whose first response was for me to get a new router.  Did that already, so then they responded that my modem in the house needed to be replaced with a new one from them. (Note I was a TimeWarner customer, Spectrum took over, line speed is better, but was not up to minimum advertisments.  It is now.)

Long story short they replaced my modem with a Ubee modem/router.  In other words I now have 2 routers.  The line speed tripled for both the NetGear and Ubee router connections.  I currently have the NetGear router directly connected to the Ubee router via etheret, and the Ubee is connected to the house cable line.  I tested the range in my yard at the farthest point and the Ubee is not seen, but the NetGear router is.  I am wondering the following:

- Is the NetGear Router an expensive overkill, maybe there is a recommended Extender option I should get instead?  Note the AC2600 is a recent purchase I could still take back.

- Assuming the Extender option does not save me enough, or is not better than using the AC2600.  Is it better or even possible for me to connect wirelessly from the AC2600 to Spectrum's Ubee router?  Since my internet provider cable comes into the basement, where I currently have the Ubee and NetGear routers, in my 4 split level house (think bi-level shift half of the house up 6 to 8 steps), does it make sense to move the NetGear router to a higher floor, to give better range to the upstairs floors and corners of my yard?  I am not looking to sit at the corner of my yard on my laptop, but while doing yard work I do like to listen to music, answer the phone etc.

So bottom line is it worth keeping the AC2600?  Is there a better cheaper option for network extension?  If I keep the AC2600, is there a better way to setup my network than having 2 routers next to each other in my basement?  Will they interfere with each other?

Note there is not a great option for moving the internet provider cable upstairs, all my walls and ceilings are sheetrocked, so at least the Ubee is easiest stuck down stairs.

Thank You for any comments or help.