We’ve had multiple customers experiencing NetScaler VPX connectivity issues after applying specific VMware patches to the ESXi host hosting the NetScaler VPX instance. The NetScaler management interface and all virtual addresses become unreachable, and HA will break. This problem can occur after patching the ESXi host to version 5.1 Patch 6 (Build 2191751) or version 5.5 Update 2 (build 2143827).

There are two possible solutions for this problem:

  • Host your NetScaler on and ESXi host that is not patched yet
  • Add the following line to /flash/boot/loader.conf (create the file if it does not exist) and restart the NetScaler virtual appliance.
    hw.em.txd=512

You can find the related Citrix and VMware KB articles here: