In case anyone needs an update…as Mr-914 said, QQ file transfer is the fastest and most reliable for sending files. HOWEVER, QQ is known to be lax in their security and I personally know of many colleagues whose QQ accounts were hacked.
Nonetheless, QQ is your best bet as wetransfer, Google Drive, and many others have all been blocked. VPNs will also often be blocked, so if there’s anything that you need to send in a hurry, don’t let VPN be your only option.