Proxy

For some reason I'm no longer able to get updates for my 12.1 system,
after a time it invariably gets "Cannot access installation media"
whether refreshing repositories or trying to get a package. Perhaps it's
my satellite internet with bad ping times, but my 11.4 system is able to
get updates with a couple of retries. I'd like to try making the 11.4
system an Internet proxy for 12.1. Is there a reference that explains
how to do this. Thanks, Paul
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