If you have issues with the network on your please check the following:
Make sure the jumper switched to a boot mode
Try to install Hypriot OS if you are using another OS
Check the ethernet switch and network chips for extra solder paste. If you see some tiny silver balls around the chip, just scrape them away with a needle or any other tool.
If the nodes on the Turing Pi 1 board are boot looping, there are few things you should check
Check if you use a proper power supply. You should use 12V, 5A, 60W power supply. Please read more about the power supply here.
The second thing that could cause this issue is if you run apps that require a lot of RAM and the total RAM on the board is insufficient.