You haven’t yet provided much information beyond your ability to ping, so I’ll give some general ENI advice.
Upgrade to the latest firmware, especially with a series D. Upgrading the D’s I have to 3.22 made a world of difference to me. Also, even if you aren’t using external power for the ENI via the terminal strip, ensure that the ground lug is grounded.
These two things have reduced my ENI troubles drastically.
Shawn