Currently, the maximumReceiveSize parameter used by the DCB tftp server is undocumented. It defaults to 50,000 bytes, and increasing it is recommended / required.

Docs: Add a new topic in the operation>deep-dive>device-config-backup/configuration.adoc file after the “Configure TFTP IP address” topic:

Configure maximum backup file size

By default, the maximum file size the internal TFTP server will accept when {page-component-title} receives a backup is 50,000 bytes. We recommend that you increase that size:

[include example, above]