Jumping on this thread regarding the SB6141 HW v8 problems. Describes my problem perfectly. I've tried the direct support on DSLReports and got absolutely nothing in response.
In many areas IPv6 doesn't work or is horribly slow and times out. Throwing different modems at it might help, but the underlying issue is at TWC's end.
And yes, TWC presently has no working config provisionining for 6141's with Ver 8.0 hardware.
The CMTS keeps trying to roll it back to ver 7.0 which fails.
From a TWC rep on DSL Reports on 2016-Jan-22 4:31 pm - "I'm sorry, we reached out to the division and we have not been provided any plans regarding whether the SB6141 hardware version 8 will be supported with IPv6."
I have the same problem. I recently switched to the 6141, hardware version 8. I just thought I'd add my name to the list of interested parties.