Acronis Backup Cloud: HOW TO purge FES address cache from agent

Symptoms

1. You have changed your Acronis Storage Gateway/Acronis Storage 1.5 external IP or DNS name.
2. You've successfully re-registered the storage according to instructions from KB https://kb.acronis.com/content/59997 to apply these changes to Acronis Backup Cloud.
3. Backups for some clients are failing with the following error: