Not sure where you were advised to turn off the Firewall but it was not a good idea to do so, the suggestion made by myself was that you give the Firewall permission to allow Reason 10 and the Epic games launcher to pass and connect, another guide here you want the Allow an app through the firewall details.
Running: Malwarebytes Service
Running: MaskVPN Service
The above two can cause connection problems as can having multiple browsers, all are secondary to your most pressing issue, you are close to losing not just Windows but also all of your personal data on both drives.
Partition 1
Partition ID: Disk #0, Partition #1
Disk Letter: C:
File System: NTFS
Volume Serial Number: A8FEBE9B
Size: 464 GB
Used Space: 450 GB (96%)
Free Space: 14.6 GB (4%)
Partition 0
Partition ID: Disk #1, Partition #0
Disk Letter: I:
File System: NTFS
Volume Serial Number: 6283BD59
Size: 931 GB
Used Space: 920 GB (98%)
Free Space: 11.5 GB (2%)
For Windows to be able to run efficiently and to be able to update you need to have between 20 and 25% of the partition or drive available on a HDD and an SSD between 10 and 15% as free storage space at all times, if you don`t you risk Windows becoming corrupt or not being able to update which puts you at risk of malware attack.
Data only storage devices should not be allowed to get any lower than 10% of free storage space of the full capacity of the drive/partition on the drive, this also to avoid data corruption.
Please note that storage devices can physically fail if the amount of free storage space is allowed to drop below the required 10 or 20/25% minimum.
Uninstall as many unused programs, games, videos and music files as you can and get yourself another means of backing up to, post back when you have between 20 and 25% free storage space on the C: drive/partition and we can go from there.