Has anybody a idea what possibly whent wrong with my edge 705.
i ride a track 2 months ago and afterwards the gps signal was looking fine in garmin connect.
Yesterday i ride again the same track and when i look back i ride on roads where i didnt go.
These roads are close to the ATB track. a lot of straight lines where made, believe me there is no straight line on this track.

Please help

What probably happened was that, on the day of your second ride, the GPS was having some accuracy problems that caused it to think you were riding closer to the roadway than you actually were. After that, a feature called something like "snap to road" took over. With snap to road (or whatever Garmin calls it), if your GPS position is close enough to an actual auto road, it will just assume that your GPS is a little bit inaccurate, and try to adjust your track so that it looks like you are riding on that road.

Why was your GPS position erratic and why would you ever want a snap to road feature? Well, lots of things can affect GPS accuracy on any given day, such as weather and atmospheric disturbances, number of satellites in view, nearby electromagnetic interference, satellite ephemeris and clock errors, etc. This is completely normal and doesn't mean your Edge 705 is necessarily defective. So snap to road is one trick many GPS units use to clean up the noisy track data by making certain assumptions about your riding style. If you're on a road bike or in a car, it's a pretty good assumption that you will in fact be riding on a road. It's a terrible assumption, however, for ATBs or other off-road activities. The good news is, you can usually can turn this off somewhere in the GPS menus. I'm not sure if the correction is applied to the actual track points in the GPX file, or just to the display when it renders the track. If it's applied to the GPX, then your original ride data is probably lost, I'm afraid.

I own a 705. Personally I never liked how long it took to find the satellites. I no longer use mine. Metaluna didn't mention this but it might make a difference depending on what version/year of Garmin Map you are using. Assuming Metaluna is right you might need to turn off the "snap to road" feature if indeed it uses one and then track your ride again. Hopefully that will solve the issue.

What about your other gps options; how did they go? Like speed accuracy. ETC. Have the laps feature? If so, did it count past 1 lap, when doing more than 1 lap?? Ever contacted Garmin customer service? If so, what were they like? Spoken to more than 1 rep about the SAME issue or question (because you weren't happy with the lack of detail, context etc from the rep. Or maybe even the rep not answering your question at all -- as this was one of my results. If so, what was the consistency of the answer, when comparing each rep -- to the same issue?? (you may have called about the same issue several times, as you forgot part of the answer from the previous;. Or [what speak like] a new rep was previously spoken to --- and you chose to call again to speak to one who you had more confidence in.) ETC