I inspected the messages the player is sending with Wireshark and found out that it actually does try to get the files through port 80. The URL is HTTP so the player code somewhere changes the address. Then I found this in the CHANGELOG.md file:
27.08.2018 - (unstable)
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- Only HTTP download type is supported for now in RequiredFiles
So it seems that if I wish to get the player working I’ll have to enable HTTP on the server. The player handles everything except the file downloads with HTTPS.
EDIT:
I did some more testing. I now managed to force HTTPS on the server but URLs turned into HTTPS return empty files.
EDIT:
The player suddenly works. Not sure how. I did multiple reinstallations, tried different URLS, did XMR reconfiguration. The default HTTPS URL started working.
I’ll try the reproduce the problem in the future, and report here if I find a precise solution.