GPS Antenna required but which one...?

[Dorchester2]

Thank you for your thoughts.

But I've forgotten to tell that yesterday when starting up I'd put the GPS test app on the Erisin while I'd started Waze on my phone.
And while the Erisin struggled so many km catching the signals, from the very beginning Waze on my phone was working a treat, and the phone was located just in front of the dash with the Erisin aerial hidden behind.

And now I'm just back from the outside garage where the 75 is parked, and being close to the car - sliding door shut - I've launched exactly the same GPS test app as on the Erisin.
Guess how long it took to my Android phone to display the 3D Fix?
No more than 3 seconds!

Conclusion:
- as we both of us have exactly the same Erisin with the same reference (but not exactly the same aerial),
- as when driving, my LG phone is getting the 3D Fix very quicly when Erisin needs 20 minutes or more,
- as when being standstill in the garage Erisin cannot get the 3D Fix when my LG phone needs only 3 seconds,

where could be hidden the culprit?

I can only see 2 answers at the moment:
- either Erisin aerial indeed irrespective of the precise place where it could be put on in the car)
- or maybe Erisin software. There may be a failure in my sample but I've learned everywhere it's of no use to contact the useless customer service.

Anyway I'll try your suggestion next time: testing Waze outside of the garage before starting, but when it'll be a little milder outside.

And in the end if I can't get any better result it'll not be the end of the world: I can get radio, music, Torque, hand free phone you name it on Erisin, while using Waze on my phone. Best of both worlds: I am still optimistic!