MN-500 Unstable Connection

I'm running an MN-500 wireless network with a MN-510
adapter. Network ran fine for about a year, then the DSL
went down for a few days and since it's come back up the
connection for the MN-510 wirelessly connected computer
has had an unstable connection. Every 10-15 minutes I
lose my internet signal. If I go through the base
station manager and release/renew the connection, it
seems to fix the problem, but only for a few more
minutes. Any ideas? thanks in advance