Your attenuation is high but it has nothing to do with the issue, the problem is with your down SNR. I also think that it is not from your end, the underground phone cables that are installed from the cabinet to your house might be too old. Mine were installed back in 1993, the standard Ogero phone cables (while they should be at least Cat5e), they can be easily affected by the underground power cables.
That time when your SNR goes down might be where the street lights kick in or something else nearby. In my case, there is a nearby shop where I can tell if it is open or closed just by checking the SNR. When the shop's electricity is on, it affects my down SNR.
My problem is very similar to yours, you can check it in this thread:
https://lebgeeks.com/forums/viewtopic.php?id=17815. I didn't update the thread, I just got sick and tired from the problem and waiting for FTTH or FTTC to be done because I am sure that Ogero has to fix the underground infrastructure. Also after I complained to Imad Kreidieh (I can explain in detail what happened) two guys from Ogero came by and made a test from the cabinet, the test showed that the issue is not from my end. They told me to lower my speed... *facepalm*
I can confirm that syncing to ADSL2 will make disconnections much less frequent, let me know in case you managed to fix the issue, what was the main cause, the solution... Good luck.