I can access the adtran in question & I am able to telnet & it is working fine with a SIP trunk. I can get to the HTTP Menus & perform everything I need to do in the menus except the following (System -> Utilities -> Configuration -> Download Config).
The adtran is:
! ADTRAN, Inc. OS version R13.4.0.E
! Boot ROM version 14.04.00
! Platform: Total Access 908 (2nd Gen), part number 4212908L1
This also occurs with another Adtran with a similar configuration on a different IP address.
Not just on my PC but others & on different web-browsers.