After the last blow I was kind of disappointed and almost about to give up. The modems ethernet ports all decided to die a few weeks later too. Luckily I had a new modem readily configured on standby.

I'm not really sure how to put this.
OMFG Yes! IT WORKS!!! OMG OMG OMG OMG!!!

Today a slowly approaching thunderstorm came and I have positive identification on strikes about 10 miles (15km) out.
I also recorded several disconnects that strikes might have been as far away as 40km.

The reason this now suddenly works(better?) is that the other day I changed out my 40cm antenna with a 2m long antenna (0.75 mm2 single coppwerwire).
Today it detected more than 24 strikes all more than 10km away.

This now appears to be a bit too sensitive for its task, but since this is just my home line its better to be safe than sorry.
This now being confirmed working will save me hundreds of $$$'s in modems and network gear in the coming years.
Not to mention the grief of beeing without a DSL-line for days due to damage and modems in the snailmail.
There might be an issue with the software where the reconnect timer is not being reset when new strikes are detected.
I will have to do a code review on that.


Finally one big thanks to the author of this detection circuit: charles@wenzel.com
also check out more of his awesome work at http://www.techlib.com/default.htm / http://www.techlib.com/electronics/lightning.html

Thank you so much!