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NextCloud sends SomeFile.doc to User (Egress bandwidth from your server to CloudFlare, may or may not be billed depending on your provider).B2 returns of Path/To/SomeFile.doc to NextCloud via CloudFlare (B2 Egress via CloudFlare, free Ingress bandwidth to your server from CloudFlare, may or may not be billed depending on your provider).NextCloud determines contents on B2 is Path/To/SomeFile.doc via CloudFlare B2 (Egress bandwidth on your server for B2 API call, minimum, may or may not be billed depending on your provider).CloudFlare accepts User request, and forward to your server (Ingress bandwidth on your server, may or may not be billed depending on your provider).User request for Nextcloud/User/Files/Path/To/Some/SomeFile.doc.Depending on agreement, you'd have to pay for what bandwidth flowing into your server from CloudFlare (B2) to service the data. In the second flow, the request flows as: Your Server -> CloudFlare -> B2. Depending on agreement (i.e.: if you have unmetered bandwidth with your server provider), you'd have to pay for what bandwidth flowing from your server to CloudFlare to service the user request. In the first flow, the request flows as: User -> CloudFlare -> Your Server.
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There's two connection flows to think about: It is a bit complicated, but yes, you can get free bandwidth on a very large NextCloud instance in some specific situations.
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