One other thing to be mindful of is that whenever the scripts recommence logging e.g. when the PC is switched back on again, they "catch" up with the modem's stats that are clocking up all the time the modem is switched on, regardless of the PC and or router being switched on or off.
This can sometimes appear as a sudden burst of errors that wouldn't show as a burst if the scripts had been logging throughout.
One way to deal with that would be to delete the offending "catching up" row in modem_stats.log each time the scripts recommence their data logging.
The other alternative would be to leave the scripts logging 24/7 so that any changes will be shown more gradually as the data is that way updated every minute.
I'm not a great fan of dimmer switches either.
Even when switched on full, a humming/buzzing sound can quite often be heard that probably causes some interference on xDSL signals, especially at the higher/weaker frequencies involved in VDSL2 provision.
Just between the two of us... If a certain black feline (who doesn't even have a VDSL2 connection of his own to play with) hadn't stuck his paw in many months ago, these Windows scripts wouldn't even exist at all, especially if that kid with an asbo against his name hadn't found the unlocking key for us in the first place.
EDIT:
Make the donation toward your electricity bill, so that you could run the scripts 24/7 for a full week (8 days would be better)