Hubic - backups fail from synology nas

Hello team,
I have been using hubic with my Synology NAS for almost a year now. It is the 3rd time that after setting up my backups, they run smoothly for several months and then they just start failing.
I did an investigation with Synology and the outcome is that the cause of the issue may be on hubic.
The particular entry in my logs that indicate a failure to upload a file look like this:
#10: {"error_class":"swiftclient.exceptions.ClientException","error_code":503,"error_message":"Object PUT failed","success":false}
2018-06-22T02:00:04+01:00 bud img_worker: openstack_error.cpp:70 send_file:594 failed, {"error_class":"swiftclient.exceptions.ClientException","error_code":503,"error_message":"Object PUT failed","success":false}
2018-06-22T02:00:04+01:00 bud img_worker: (15277) file_transfer.cpp:787 failed to sendfile to [bud-vol2-bak.hbk/Pool/0/4/782.bucket.20] from [/volume1/@img_bkp_cache/hubic_swift_default_.quOhmB/bud-vol2-bak.hbk/Pool/0/4/782.bucket], data_hot=[0], error = [1]
2018-06-22T02:00:04+01:00 bud img_worker: (15277) file_transfer.cpp:621 failed to sendfile: trg_relative path: [Pool/0/4/782.bucket], err: [1]

How can you please help me troubleshoot and fix the issues I am having with my account?
Thank you in advance,
kind regards.