I reserve my right to reply to this only as it contains a question directed at me, although Orangemm has requested that I no longer post to this thread from this point on, which i've agreed to do, but for other reasons than to satisfy his own personal preferences.
If you look back through my posts on this thread, I linked twice to a thread that started mid 2016 where people with iPhone 6's were claiming the same issue but blaming iOS 9 (although if you read on carefully, you can tell that people had started blaming iOS 10 without realising the thread starter had blamed iOS 9). It's a good read. Actually, it's much more interesting, enlightening and tolerant than this thread. It highlights that the issue was solved for the major majority with a hardware fix. Either the antenna flex cable and/or the GPS antenna.
Quote WooDz "However here is the crux in all this Hardware/Software debate... If it was indeed a hardware issue then why would the problems only start since the introduction of iOS 11, surely a hardware fault would have been apparent in all previous iOS versions... Of which they were not."
If you read the thread i'm recommending (link below), it's very clear that this is not the first time people have associated a major or minor iOS release with an issue with their phone, or indeed a GPS issue. It probably won't be the last either. The problems you mention may seem wide spread but it is totally not if you do your sums. I've made it clear before that the figures don't actually add up due to this affecting only a virtually pico sized percentage of iPhone 6 owners. As I am probably upsetting Orangemm (he can't resist reading my posts!) i'll stop now but do please read the whole thread...
This is the thread
iPhone 6 GPS not working
Before I go. here is the same issue reported after iOS 10.3 from April 2017
https://discussions.apple.com/thread/7909006?start=0&tstart=0
An earlier one when iOS 10 came out from Oct 2016
https://discussions.apple.com/thread/7693853?start=0&tstart=0
There are more if you search.
Regards. Rimmer