As a negative, I suggest the HG612 is no longer the modem of choice, but may be a reliable fallback.
I say "may be" because many on eBay will now be knocking on a bit, with cheap components that could be on the way out. I'm also convinced modem technology for VDSL2 has moved on since they were introduced. Plus of course when Openreach first supplied them the profile in use was 8a, not 17a.
Late last year I tried three other pieces of kit, each of them reporting an Available speed about 10Mbps higher than either of my HG612s. I can't report the actual as the line was banded at the time.
The banding is no longer there and I have now been on 65258/14193Kbps since 18 February. My highest ever with an HG612 was 57700Kbps or so.
Available is showing between 66 and 67Mbps depending on the varying noise, with the noise margin moving between 6.1dB and 6.3dB. Recently the odd spike to 6.4dB.
I'm using a Billion 8800NL R2 in combo mode. A bit expensive for pure modem/bridge mode.
Kindness isn't going to cure the world of all its awfulness but it's a good place to begin. Daisy Ridley.
My broadband basic info/help site - www.robertos.me.uk.
Domains, site and mail hosting - Tsohost
Connection - AAISP Home::1 80/20. Sync 65258/14193Kbps @ 600m. BQMs - IPv4