Typically when upgrading a V-Series panel firmware (U-Boot, Kernel, Application, Display Application) the Eclipse upgrade manual indicates one panel upgraded at a time when performing the procedure using the TFTP server software on a PC direct connected to the V-Panel ethernet port. 
Using a standard ethernet switch and standard CAT-5 cables it is possible to upgrade multiple V-Series panels simultaneously manually.  It is best to stagger the upgrades to the connected panels by at least 5 to 7 seconds in order to reduce the number of resends of the firmware files to the connected panels by the TFTP server.  Using this procedure up to 3 panels at a time have been successfully done.  This allows the upgrade to users of large numbers of panels to be done in a timely manner provided the panels can be removed from existing locations and upgraded in one central location.