Why is there limited connectivity on my network, and why can't I get on the internet?

[haphazard_artist]

I operate on a PC, and my internet is ATT Yahoo DSL with a internet modem. The interent cable goes from the modem to the wall. Why sometimes is there limited or no connectivity? I see a icon on the blue task bar of two little computer screens and a exclamation point (!) . I try to repair it, but it doesn't work. Why does this happen? Is it the internet provider? My computer? The network? (What is a local network?)


haphazard_artist