TL;DR Downgraded Fritz firmware to 99.05.22. Back on DLM1. Happy!
Thought I would share another firmware downgrade success story. I must apologise for the lack of screenshots. I wasn't intending to make a post on this but since a few people have been talking about downgrading recently, I thought I should share.
Here's what everything looked like back in July when my Snap VDSL went live, using the latest firmware:
Given all those errors it wasn't surprising that DLM kicked in and I moved to DLM2 and then finally settled on DLM4. From this point I would get a resync maybe once a month where I would move from DLM4 to DLM2 and then back again as the error rates crept back up. My line sync also settled in around the 47000-48000 mark. I was happy, the speed was good, but we all know us geeks like to tinker...
On November 13 I finally got around to downgrading the firmware on my Fritz 7340 to the 99.05.22 version, and then proceeded to let DLM do it's thing naturally. I know I could have called Snap and got them to do a manual reset, but at the same time I was interested to see what would happen if left on it's own. I'm assuming at this point I was on DLM4 - hard to say as I believe the .22 firmware seems to report the INP values as zero even if that isn't true. I was on DLM4 before the downgrade. One noticeable difference was the lack of CRC errors, they were zero, where-as on the latest firmware it was always reporting a value <1 per minute.
On December 1 I had a resync which I believe moved me to DLM2, again hard to tell. Still zero errors.
On December 3 I had another resync and this time we were back at DLM1! The first thing I noticed was the CRC errors heading towards values of about 400 per hour. At this point I promptly changed the Line Settings (since they actually work on this version):
This resulted in a slight drop in download speed as expected, but it's still enough for my needs. Currently this is what I'm seeing (stable since 6am December 3):
So, if you're considering downgrading, my advice is to do it. This version behaves so much better and I'm yet to see any downside.