Internet dragging / very slow.. Internet issues please suggestions

Hey Guys,

Let me set this up; so we have a group of people working that spreads 2 floors. We have say about 75 people working on one floor and about 40 working on the bottom floor.

Here is the issue, on the lower floor the internet has been super slow these last few days. To the contrary, on the floor above with the majority of people the internet is fine and wireless is great (pretty much everyone uses wireless except our printers and phones).

At first when connecting to a port, in the bottom floor, the internet worked perfectly fine; so, we were starting to assume the access points had something wrong. But now (sometimes) even the wired connection is dragging.

We have two access points down there connected to ports. Maybe one access point is bad? But what if the wired connection is starting to be slow? Are we starting to run into capacity constraints? What do you guys suggest. Again Everything is perfect for everyone on the above floor which has the majority of people btw.

p.s. Everyone is under one main router the Sonicwall 250m in case anyone was wondering.

Thanks for any help in advance :)