Throttling rules must be created for all NICs for the machines on which Veeam Agents will run. When a job runs, a port for the veeamagent.exe process is opened on each NIC of the source and target servers, even if that NIC is not responsible for source agent to target agent data transfer. Below is an example of how the rules would need to be applied.
Source VMware backup proxy or Hyper-V host/Offhost proxy IPs: (2 NICs) 10.0.0.30, 192.168.1.35
Target repository/proxy server or target Hyper-V host (in the case of Hyper-V replication) IPs: (2 NICs) 10.0.0.31, 192.168.1.26