I would suggest to turn off the Wi-Fi on your Spectrum wireless router. Yes the R510s would be much better at providing coverage and capacity but also can do the following:
1. automatically choose the correct channels to optimize your network by automatically detecting interference and moving to a less congested channel. Something most likely your ISP router cannot do.
2. Provide better RF capabilities using Beamflex.
3. Monitor your switch
4. if configured, provide you alerts
You most likely need the spectrum wireless router if that is the device that provides you internet but also is the device providing DHCP addresses to your network. You can though turn off the wireless radio.