Thanks for posting your question on the forum!
What firmware are you running on the 1335? I would recommend upgrading your firmware to the latest maintenance release (currently R11.4.2) and retesting. If the issue persists, please contact Adtran Technical Support to troubleshoot further. You can contact Adtran Technical Support in the following ways:
- Open a webticket by clicking on this link: https://www.adtran.com/openacase
- Open a ticket by emailing firstname.lastname@example.org
- Open a ticket by phone by calling 1-888-423-8726
Let us know if you have any questions.