Thanks for the reply.
Tried a bunch of things now. Such as various SSL settings on Win10, disabling Router and Windows firewall, restarting router, clearing browser and router cache and more but nothing seems to work. Still getting the SSL error on desktop.
Tried it with my phone over 4G and the page works fine, as well the downloads.
I have no idea what changed since last Thursday and Saturday.
Thanks for the help though, guess i'll have to stick to downloading via phone and then file share to my PC.