This is a simple question. Is there a way to set the Network manager to not shut down when going in to suspend mode?
No, that is not that simple at least. Some machines support wake on lan (WOL), such that you are able to wake the computer from a hibernation state, but I am not sure whether that works with suspend mode. Setting up WOL is not straightforward and known to cause headaches.
Suspend mode generally freezes the system and provides just enough energy to support RAM, so that even if you keep power your hardware network interface, you won't be able to do anything with it.