Hello,
The issues you are having are host based issues / configuration problems.
From the host side there are considerations.
If you have two NICs configured on two different subnets how are you handling failover?
Using VEAM are there two backups or one? Since you mentioned active and archive you have to consider how the archive is working? Is that using a VEAM snapshot of the active backup?
On the host side, MPIO failover should be configured so that you can perform path failover. With two different subnets you will have to consider carefully how that path failover is working. You will need to confirm and test that your failover pathing policy is actually working correctly. You also need to check and confirm the queue depth and multipathing policies are set correctly for your server and NICs. For example MRU or RR? This will depend on hardware and OS versions.
It sounds like the server can handle the load once configured correctly for VEAM and ESXi. However, be aware that with newer versions of ESXi ATS/VAAI may not be compatable with the P2000 firwmare. You should review SPOCK for the latest firmware compatability with the P2000 and ESXi to ocnfirm.
Sorry I cannot give a more firm answer but there are a lot of configuration unknowns here which makes answering your questions fully very difficult.
Cheers,
Shawn