Seems some unnecessary agro here. Fact is either hardware or software issues can affect GPS functionality.
First, a few pertinent facts about getting a location.
The GPS system as employed by mobile phones has an accuracy of 5 metres on ground position and 3 metres on height assuming multiple satellite acquisition and no interference from building reflections or other effects.
Cell tower triangulation gives position to hundreds of metres routinely and down to about 30 metres where there is dense population of towers.
iPhones use 'assisted GPS' in which interpolation from cell position, nearby WiFi networks and Bluetooth are used along with GPS to try to get best accuracy and as quickly as possible. In urban areas this combination can be very good in compensating for lost lines to satellites because buildings get in the way.
Now to the problem. My iPhone 6s+ recently gave very bad data during walks and on the golf course. Definitely not accurate enough for normal use and sometimes wildly out. On careful examination of data and comparing with historical tracks it showed that in town it was about 30 metres off and out of town up to 400 metres off. That is exactly what would be expected with no GPS availability and the phone doing the best it could with cell, wifi and bt signals only.
Downloaded GPS diagnostics app and it showed as expected that location services was not acquiring any satellites.
It was able to turn off and restart the GPS module but could get no satellite signal. That looks like an antenna issue, or possibly a GPS chip fault but certainly a hardware fault.
Those stating that location started off close got worse, then at times got better therefore had 'intermittent GPS' almost certainly have a broken GPS antenna or chip and NO GPS since the cell, wifi, bt interpolation will give exactly the results reported.
Advice to reset software settings are worth trying since occasionally things get confused so you my get a solution.
My advice is download GPSDiagnostics, that will tell you exactly how location services is working and in most cases show that your phone cannot aquire any satellites, so you need o get the hardware fixed.