Lets start with the very basics.
1- establish if you can access the "WebAcess" UI interface from within LAN
open browser and enter http://IP:9000 where IP is LAN IP address of the unit. example http:192.168.11.5:9000
if you can not see WEB ACCESS UI from LAN . You will have to recheck your setup. (make sure at least one or more
directory has enabled option for WebAccess .)
2- If your router port forwarding is set correctly you should be able to enter : http://buffalonas.com/trusty14
where trsusty14 is the "BuffaloNAS.com Name:" specified by user.
if above does not work , please check if you have any proxy settings or 3rd party add-on .
re-check with another browser and finally re-check port forwarding in router.
Let us know if you have any differentiates .