Hello @paul-phillips-2. Your route looks like it should be very entertaining. I zoomed in on a few waypoints at random and found several that were not placed accurately on the road. Regardless of device or app used, this can cause problems in navigating a route if not corrected. Some of the waypoints checked cause a turn in the opposite direction to that clearly intended, followed by the need for a U turn after a short distance. I recommend you zoom to the maximum into each waypoint on your route and, where necessary, reposition accordingly.
If you do decide to use a map layer other than Open Street Map, as suggested by @Nick-Carthew, it would be best to change that first and then sort out the waypoints. Differences in spatial data between map layers can vary the position of roads enough to leave you back at square one if you don’t do it in that order.
Have a great trip.
