My server goes down and I do not know why

[dryanta at r2d2.reverse.net]

Hi my name is Phill. I am having an issue with my freebsd webserver that
is behind a freebsd nat/firewall and was wondering if you can point me the
right way to resolve my issue. My connection to my ISP (microwave wi-fi)
keeps dying every couple days and I do not know where to start to
determine the issue. What are the basic diagnostic steps for determining
why my connection keeps dying every couple days? I do not know if it is a
problem with the wifi, routing, or nat. If it is a problem w/ wifi i want
to compile a bunch of info to bring to isp to be like 'you idiots are not
upholding sla!' and if it is my internal configuration I would like to
simply resolve the issue. What is necessary for me to do for assistance in
this issue?