I think the key here is the error you get ‘certificate signed by unknown authority’… Its trying to verify the cert your using and it cant because the cert is saying ‘hey, go out on the Internet and double check this’… or ‘hey, double check this host name on the cert with the local CA on the network will ya’…
Either way, its failing to do so.
This thread has the answer I am pretty sure:
Since you on a ‘closed’ network and I doubt you are running your own local CA (but check with your IT guys in case) you need to set up the certs as per that thread.
Hope that gets you pointed in the right direction.
(Oh, it probably worked OK on the Pi because as you suspect, it did not care to do the look up… ‘Yeah yeah, no worries, just jump in and grab the data… shes right mate, I have no idea who you are, but I trust ya’…)