I have not yet been able to get internet access, but I have managed to update the navigation software.
The TW satnav is based on Windows CE, and the best program I've found to work is "mapFactor Navigator free". I will recommend getting a second SD card, and keeping the original one unaltered, for warranty's sake, and as a backup. The latest maps available for free are from Feb 2018, and you will have to manually update them when you need to.
