connection failing

[nepal]

I have a new installation of 7.10.

I can run a browser and browse the internet.

If I run the install programs manager and it tries to make a 
connection to a mirror, the connection just fails every 
time I try. I have had problems with other linux distros 
and avahi (someone on another list told me of a problem 
with this and some modem/routers which includes the netgear 
dg632. The problem lay in names not being translated into 
correct IP addresses ).

Does anyone understand what I'm talking about and can help 
me fix this please?

TIA

nepal.