TWC in most areas offers native IPv6. Here is how I got IPv6 working with pfSense in my area (Raleigh, NC) with router advertisements and stateless autoconfig!
For whatever reason, often I had to reboot pfsense at times to have changes appear. If anything appears odd or not working, reboot. 🙂
Also the various known methods of pfsense/IPv6 with ISPs such as Comcast on this page do not work for TWC in my area at least from my testing.
1. Setup WAN
For the WAN interface, set the following:
IPv4 Configuration Type: DHCP IPv6 Configuration Type: DHCP6 DHCP6 Client Configuration > DHCPv6 Prefix Delegation size: 64
2. Setup LAN
On the LAN settings page, use the following settings:
IPv6 Configuration Type: Track Interface Track IPv6 Interface: WAN IPv6 Prefix ID: 0
You may then have to restart clients on your network or restart their network services.
Note! I also had to uncheck Interfaces > WAN > Block bogon networks
This for some reason blocked some things that IPv6 requires to work! So leave that blank (unchecked) for WAN!