WAN Accelerator error invoke RPC function

[JayMeath]

Hello,
When running a replica copy from backup I receive the error
Error: Source WAN accelerator error: Cannot invoke Veeam RPC function.
This happens on more than one job and appears to fail on the jobs within a minute of each other.
The jobs are not using the same source or destination WAN Accelerator.
I deleted and recreated the WAN Accelerators.
These jobs are between 2-5TB is size I only have a 20mbps connection (low latency) connection between sites.
An initial replica will take days to complete successfully.
The data does not change much so after the initial sync the jobs will typically only take a few hours.
Does anyone have any suggestions?
Running Backup and Replication Version 9.0.0.902
Thank you in advance for your assistance.
The support Case ID for this problem is 01714129

[JayMeath]

Hello,
There have been no replies so I thought I would create my own and update the status.
The functionality is greatly improved although I'm not sure it's entirely fixed.
I thought this information may be useful to someone else so I'm including the steps/changes I did.
When working with support several recommendations were made.
1. I was having problems with time sync between the servers
2. I increased the RAM on the WAN Accelerators to 16GB
3. Disabled User Access Control (UAC) on the servers in question
4. Set SSDP discovery host and UPnP Device host services to start automatically
5. Installed all Windows updates
6. Disabled TCP checksum offload for IPv4 on the network cards
It was set to RxTx
7. Upgrade VMware Tools to current version
8. Upgrade servers from Windows 2008 to 2008 R2