Let me clarify: Issue is with "DDNS service" option found under 'Tools+Dynamic DNS", issue is not with DNS lookup service from my carrier. (Note: If you are having issue with DNS lookup and using AT&T DSL service, issues have been found with DSL modem's DNS scripts crashing on modem-use of Google's DNS server on router is recommended).
Use of DynDNS.com service does not appear to be working with firmware upgrade.
Any suggestions related to this issue would be appreciated.
Any else having same issue due to firmware upgrade, please post.