So, I was smashed quite a few times in a row without me seeing any real progress. In the end I managed with an approach I had rejected as short sighted, but due to the enemies coming in quickly and hard it seems it's the only way to go.
Overall it was frustrating at first but great to finally beat it. I might have missed that completely, so you could add for example a beginner's difficulty so people don't just fail again and again and eventually quit.
I like how not only nodes but also connections can take damage, so you get rewarded for building many connections! And nice to see some other node based game. ;)