I thought that was with the laptop plugged direct into modem and not via your network switch, however I am confused at what's connected to which device on the LAN and wan.... and if you've ever had full internet (not just sync) at the same time.
To get linestats on the LAN side of you switch you need 2 cables. There is a way to do it with one cable I think, but it iinvolves configuring a new interface....and could be further complicated because of your static ips and I've no idea how that would work with the firewall.
I'm a bit out of my depth because of the non standard configuration.