Help Needed: "Error Connecting to Server" While Uploading Course Backup File

Dear Moodle Community,

I am encountering an issue while restoring a course in Moodle 4.5+. I am trying to upload a backup file of less than 500 MB, but I consistently receive the error: "Error connecting to server" (screenshot attached).

I have tried the following methods to resolve the issue, but none of them have worked:

1. Cleared the cache of my browser, purged the Cloudflare cache, and purged the Moodle cache.
2. Disabled my Cloudflare firewall and attempted the upload again.
3. Split the ZIP file into parts, but Moodle does not support extracting split files.
4. Tried uploading the backup file to my Private files first, but I encountered the same error.
5. Increased the upload limit in Moodle and on my Hostinger server. Moodle shows no limit on file uploads.
6. Verified all PHP configurations on my Hostinger server to ensure they support large file uploads.

Both my Moodle version and the backup file version are Moodle 4.5+, so there shouldn't be any compatibility issues. Despite all these attempts, the problem persists.

Could anyone please guide me on how to resolve this issue? Your assistance would be greatly appreciated.