Perhaps what we saw was a conventional explosive in the RV triggered by a DEW.
The light pole video shows a sweeping beam towards the explosion.
The street surveillance camera shows an explosion across the street from the RV. Perhaps this blew something up from its initial beam and then swept to the bus and ended at the servers.
The RV was a cover for a DEW attack on the AT&T location?
The DEW would have been a redundant attack on electronics in the building.