Does
teamviewer work if you installed it on each PC and connected? I use this frequently to access and share files.
What programs are you using when you are accessing shared files?
What region are you located?
Are you wired or wireless connected to the router?
What ISP Service do you have? Cable or DSL?
What ISP Modem do you have? Stand Alone or built in router?
What ISP Modem make and model do you have?