By clipping the $20 coupon on Amazon, the ARRIS SBG6950AC2 Modem AC1900 WiFi Router is only $140. The ARRIS SURFboard SBG6950AC2 is a DOCSIS 3.0 modem with 16 download and 4 upload channels (max download speed of 686 Mbps).
The SBG6950AC2 features WiFi beamforming, 4 Gigabit Ethernet ports, and AC1900 2.4 GHz and 5.0 GHz dual-band concurrent WiFi. This combo unit also includes a 2-year limited warranty.
Note: This modem/router combo unit is minimally qualified for Charter Spectrum. In other words, the device has passed minimal testing to confirm that it won't cause harm to Charter Spectrum's network, but they do not recommend using this internet device.