PoE switches are nothing special they just run a special hardware signaling between that port and the end device. It just allows a end device that need PoE to ask the switch for it. In every other way a PoE switch is no different.
The problem I suspect is this switch can be configured in a number of different ways. It supports vlans as well as basic routing. If the switch was configured as a dumb layer 2 switch then it should just work. It if has multiple tagged vlans or routing configured then you likely also have special configuration in the sonic wall.
I have never used this switch so I can't say what the default configuration is. Most devices default to all ports enabled on a single default vlan with no tagging enabled. But since you say a dumb switch works but this one does not it may not be configured that way.
You are very lucky you did not cause a huge loop if you cabled 2 cable between the devices. Very likely the switch had spanning tree enabled by default and blocked one of the 2 cables. There are cases when you can run 2 cable between the firewall and the switch but it is more related to a special design requirement rather than some default cabling.
I just did some surfing and found this article: https://supportforums.adtran.com/thread/1513
It appears the default setting is only 1 VLAN for all switch ports. What we have connected to the switch is 2 wireless routers who need PoE because they are in the ceiling. The rest are wired to wall sockets. I'm new to networking and was just looking up what a VLAN is. Would it be wrong to assume that there needs to be a separate VLAN for each router? If that is the case would i just need to access the console and assign new VLANs for each port the router is connect to on the switch and not change any settings in the SonicWall?
Thanks for the help I have 30 technologically incompetent Fraternity brothers yelling at me to fix their internet.