So many details missing here to even suggest things. What hypervisor are you using? What version of Veeam? What OS on the servers? How is the Synology attached via - iSCSI, SMB, NFS?
If you are using vSphere check this link to the help for Veeam - https://helpcenter.veeam.com/docs/backup/vsphere/replication.html?ver=120
Hi @lochana -
Welcome to the Community. Yeah...kinda needing a bit more info as Chris shared. Chris also provided a link discussing Replication from Veeam. Below is one on how to do Failover/Failbacks:
https://helpcenter.veeam.com/docs/backup/vsphere/failover_failback.html?ver=120
How is your NAS Share connected?...to a VM? If so, and you have a decent connection between source & target (e.g. a fiber connection), when configuring your Replication Job you can select ‘Direct connect’ and just use Veeam Proxies at the source and target to transfer the data using “hotadd” transport mode. (helps with performance). If you have less than 1Gbps...but above 100Mbps between sites, use WAN Acclerators in High Performance mode.
If you have a chance to do so, to help you get things going, if you have a Repository with your NAS backup at the target site, or even a VM copy at the target, you can use Seeding or Mapping to replicate your NAS. You can read more on those features below:
https://helpcenter.veeam.com/docs/backup/vsphere/replica_seeding.html?ver=120
Provide more info as Chris suggested, and we can try and suggest a bit more pinpointed info to help you out.
Ok if you are using Hyper-V then check this guide out - Replication - User Guide for Microsoft Hyper-V
Also check out the Best Practice site as well for more details - Welcome | Veeam Backup & Replication Best Practice Guide