Wifi extender for C6300

You can use AX extenders but they won't connect at AX speeds. For the extra money an AX extender would cost, I'd recommend doing with a triband extender versus the AX extender. 

Reason why is single/dual band extenders take a 50% speed reduction just because they have to use the same chip to go router---extender and then extender----device. And they can't do both at once. Versus the tribands have a dedicated backhaul. So they tend to have faster speed and lower latency. 

but if you're not needing the highest of speeds, many of the netgear extenders work that'd match your router. 

there's filters on the netgear extender page that let you filter by wifi standards/speeds, etc. 

https://www.netgear.com/home/wifi/range-extenders/

you can also check amazon, I've seen a lot of refurbished extenders on there if you don't mind refurbished.