Dremel 3D45 is shows up as offline on 3dprinteros,but is actually online

So i have 20 dremel 3d45s that are connected online through a wired connection. And over night the power went out the 3d printers were restarted. Some of them showed up online on 3dprinteros but 7 of them show up as offline. What can i do to fix this issue? Thanks

I have had to do power cycles on my printers to rejoin the network.