Simple solution first - did you try loosening the wheel lock? It's the round hub on the steering wheel that you can loosen or tighten.
Outside of that, it could be the
autopilot. Had the same problem on my
boat, and it turned out to be that. The typical
Raymarine autopilot has a belt inside that wore out after awhile, made it harder to steer even when the autopilot wasn't engaged. Your Beneteau 411 probably has a different kind of autopilot, but the problem may lie in there too.