I am looking to purchase a used SB6183 off of Ebay. I read that initially the SB6183 did not support the IPv6 but now it does. If I purchse a SB6183 which did not initially support the IPv6 am I SOL or is it just a software/firmware update that will be updated to my unit?
The firmware will be updated by TWC/Spectrum during the setup process to current version in use. As far as I know, IPv6 is working fine now on the 6183.
other IPv6 issues are global to all twc customers on all modems, usually the extremely slow DNS routing which are resolved by only one server in the US whereas IPv4 has 4 or 5 that are a lot shorter routes and more local.
Most common modems will get an instant firmware upgrade even before you have TWC provision it.
6121,6141 and 6183's have a Feb 2016 f/w date if I recall.