We have this setup:
LAN - PIX - 1721 - Efficient ADSL & Serial
ADSL is connected to Ethernet card of 1721 and have Dialer setup in the router for PPP.
There is PBR in 1721 such that IP packets from x.x.26.94 (PAT address) from PIX will be routed to ADSL.
For months, downloading large files would just die in the middle.
But last night, I changed the Ethernet interface to "half duplex" from "full duplex" and so far, never had disconnection issue after downloading GIGs of files and also transfer rate is back to normal.
Can someone explain why?
When the router was in full duplex, it was probably have been causing transmission aborts to the adsl modem in half duplex.
If you have a free wic slot in the 1721, you can install an adsl card in there and further improve the connection. However, an 857 or 877 router would be even more economical.