My favorite part of hardware engineering was the feeling of working a jigsaw puzzle where you couldn't quite see all the pieces. There is usually not one perfect hardware piece in any given network, so when you are designing infrastructure you have to be able to improvise and know the capability of the product set and its options.
Different vendors may or may not want to work with each other, in fact, many vendors design their devices NOT to work with those of other vendors (this is the difference between proprietary technology and open technology).
What makes the hardware engineer's job fun and challenging is getting the facts about what the technical need is, and having someone else worry about the business case. As a hardware engineer, all you have to do is make it work at entry level...when you start moving up you have to start worrying about cost justifications and business process integration.
Enjoy your time opening up the new box and connecting it, finding out what it can do, and showing off its capabilities! That's the fun part.