I have installed a Cisco ASA 5505 at a client site in order to set up a site-to-site vpn. Everything works fine except every so often, maybe once a week, I get a call from them to say that the Internet is not working. The Internet is adsl and is fed into the ASA by a D-link modem (dsl-300T). They have a single static ip address.
When the Internet drops, I have performed the following:
Plugged laptop directly into D-link modem and verified that it can access Internet.
Plugged laptop directly into Cisco router, no internet.
Accessed asdm and tried to ping the D-link modem from ASA. Unsuccessful (I have verified that this ping normally works when Internet is working).
I get the Internet working again by switching off both modem and router and restarting. Even this doesn't always work but usually if I continue to power down one or the other, often unplugging the ethernet cable between ASA and modem, the Internet will suddenly start working. I change no settings at all.
The vpn is inactive at present so I don't think this would be a factor.
I have swapped out both ASA and modem for a cheap Netgear adsl router and it works without an issue, but I need the ASA for the vpn capability.
I am considering changing the modem to see if that makes a difference or throwing the ASA out of the window!
Does anyone have any suggestions on how to tackle this issue?