@HeatherC... moving your router may help, I doubt upgrading (you said it's only a year old, right?) will. A mesh system will help if you are in areas where you don't get strong signal, but didn't you say everything is showing a strong signal?
I have a "Wifi Analyzer" app on my phone. It shows graphically how strong the wifi signal is and if there are multiple signals on the same channel (another thing you can change if you get into the setup). It's possible you're getting interference from a neighbor. Simply changing the wifi channel might make a difference.
ETA: Do you work for a company? Do you have a good relationship with the IT department? Or there may actually be someone else in the company that would be willing to help you out. They probably wouldn't charge an arm and a leg.