Creating a wireless access point

Hi All

I am a sky fibre customer, and as many will know, that sky do not allow customers to use their own equipment. If i was to add my own wireless router onto the sky router and configure the IP settings to create an access point would the ethernet ports still work.

Basically I have brought a NAS and the data transfer speeds are slow, because its using 100mb connection. My new router uses Gigabit, so my plan is to have the NAS on a gigabit connection, and wireless devices connect to the secondary router

Thanks