I've done a google search on this and didn't find anything relating to my problem.
My Garmin 810 head unit is approx 5 years old and in the past few weeks has been under reading the distance on maybe 1/3 of my rides.
When in Strava/ Garmin Connect and inspecting the route it's tracked me perfectly - there are no straight lines to indicate drop outs and when riding I haven't spotted any on-screen messages saying "searching for GPS" etc.
I always allow for it to connect to GPS prior to leaving and despite it being rainy/ cloudy this morning have also had problems in bright sunshine without a cloud in the sky.
I'm a daily commuter and route is just over 10 miles - I know it's trivial but at times it's measuring my route 1 mile less.
Just hoping my head unit isn't on it's way out.
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