I got a 2nd hand HH6 a couple of months ago. It works fine but the Firmware version is SG4B100021EC showing as last updated 12/05/16, so I'm concerned about not getting security updates etc.
Not clear why it isn't updating to current firmware version - have tried full factory reset etc. I can't find any advice other than 'just wait' but 2 months seems a long time. The TR69 log has things like:
TR69 event found : M Download
TR69 event found : 7 TRANSFER COMPLETE
TR69 event found : 4 VALUE CHANGE
so it does appear to be talking to the management server
I had the same problem a couple of years back where my firmware was 2 years old (probably the version you are on). I did phone BT, but at the time they weren't interested as my broadband was working fine so they didn't see it as a problem. Eventually I found a more helpful BT person on Twitter who suggest a factory reset was the only option. So I did that and it did force a firmware update.
Looking at the logs there appears to be a daily attempt to upgrade the firmware, but the device doesn't reboot and there is no change in the version and install date even if I restart
|23:05:57||14 Sep.||The Modem is installing a firmware update|
|23:05:52||14 Sep.||TR69 sending DownloadResponse message|
|23:05:52||14 Sep.||TR69 receiving Download message|
Try a factory reset by pressing the recessed button on back and holding 20/30secs until lights flash
remember to turn off smart setup when hub reboots