Try increasing the "hold-queue out".

Try to RDP with the IP address and not by DNS and do the same with the web. If you are doing it by DNS then its a domain issue.

Find out the QoS set by the MPLS provider ( usually 4 ). Try if you can make them set it to two with 50/50 bandwidth as your requirement.

Generate an RSA key pair for the Firewall, which is required for SSH:crypto key generate rsa modulus modulus_sizeNote: The modulus_size (in bits) can be 512, 768, 1024, or 2048. The larger the key modulus size you specify, the longer it takes to gene...

Looks like the Adtran is having power issue. Usually it keeps rebooting.