Which Linksys router? Model, model #, HW version, FW version please.
What happens if you connect directly to your Cox modem?
Are you connecting via ethernet, or wirelessly? If wi fi, 802.11 b or c or g or n? If wi fi, which encryption strength? If wi fi, and not encrypted, others may be using your connection.
Go to
www.dslreports.com/speedtest .
Report your upload and download speeds.
Contact Cox tech support. The problem might be on their end.
RF123