And, found that too. Sorry for bothering you with these beginners’ questions. Getting the hang of working with shortcode now, looking at all the plugin’s options. Thanks again for your work!
Somehow I was under the false impression that I needed to upload the gpx file into the NextGEN gallery – no wonder it didn’t work! Looking at some questions here made me realise they needed to be in the WP media gallery after all, and in the end I got it to work with [geo2 route=1 xmlurl=https://polderplodder.nl/wp-content/uploads/filename.gpx]. Great, thank you for the plugin!
One question, though: on my laptop, the map doesn’t show zoom options, the + and – buttons. Is there a way to get these to work?