How will this happen ?

About a common linkage between 4 hospitals ( at 4 different places probably a place where network isn’t good) to have a common connection to each other without internet because of the unstable network problem in these places.

Give me ideas of what and how I can do to make this happen being it a software or hardware with its operations.

How can it be developed to make this common linkage weather frequency or any other wireless to make it work without internet 

NB: The main problem here is to make it without internet 

That’s the explained project 

Give any reasonable idea or outline any steps that can be taken to build on this project either software or hardware ideology