Dock to Dock routing problem

[daknecht]

I have an e95 chartplotter, Navionics+ chip and Ev-100 wheel pilot on my boat. I tried dock to dock routing for the first time last weekend. The e95 plotted a route that showed exactly what I would have done manually, so that part worked fine. I told it to follow the route and all went well for the first 30 minutes or so. Then the boat wandered off the route and I had to go to standby to avoid running aground. When I restarted the route, it wanted to do a 180° turn to go back so I gave up.
1. Any suggestions as to why it would lose the route along the way?
2. If it does wander off course and needs to be restarted, what should one do? Should it pick up the route again, or will it try to go back to the start?