Did the error contain something like "cannot open NFS stream"? It may be due to the connectivity issues between Veeam server and target host/datastore: if Veeam cannot communicate with the node due to the DNS resolution issues (ie cannot resolve node01.corp.local), it will fail to upload the disk.
Product Architect @ SingleHop - Veeam Platinum Service Provider
VCAP-DCD, VCAP-DCA, VCP-NV
Veeam Certified Architect