Are you getting both blinky lights from the Ethernet ports? 
One thing, which I assumed was because I swapped an Ethernet cable from an A4+ to the T15, is that when I powered up the T15 is it stole the IP address from the A4+. Given this may not be an isolated incident caused by my switch, are you using static IPs or dhcp? If DHCP, you may want to move all the existing miners to static IPs and see if the missing miners start showing up.
One thing, which I assumed was because I swapped an Ethernet cable from an A4+ to the T15, is that when I powered up the T15 is it stole the IP address from the A4+. Given this may not be an isolated incident caused by my switch, are you using static IPs or dhcp? If DHCP, you may want to move all the existing miners to static IPs and see if the missing miners start showing up.
Definitely have normal connectivity lights. Machines boot as normal, all lights normal, but cycle due to not having a network connection. When we plug them into the connections of working machines, they do not come up. All the miners on the network are static IP, but we have a DHCP range set aside on the router for new machines. We boot them DHCP and then assign static IP's. Power cycling and resetting the machines does not help. Switching PDU, power cables, and NIC cables doesn't help. Units do not show up in our routers control panel of connected devices. I thought perhaps they had shipped us units that had already been assigned static IP's, but a factory reset would fix that. I though maybe the NIC's were being finicky with our gigabit switches, so I put them on a 10/100 switch and also plugged them directly into the router. No joy. Not sure what the problem is, but if the controllers aren't bad we'll figure it out.