A connection with 2 UDE instances to the same UAD2/UAD3 via Firewire or USB fails with connection to access device lost.

If you want to connect with more than one instance to only one UAD2/UAD3 via USB/Firewire the MultiAccess option must be enabled in the CommDev section of the Target Config File (*.cfg).

Example:

  [Controller0.CORTEX.CortexJtagIntf.UAD3CommDev]
  MultiAccess=1

Another solution is to use Ethernet instead of Plug and Play ports or to use different ports (e.g. USB and Firewire or USB and Ethernet).