Internet connection issues during video calls

Regardless of the video platform: Teams, Skype or Zoom, I occassionally get a notice saying that there is an issue with my internet connection. My speed is verified at 300 down and 40mbps up, which should be great. During one Zoom meeting I had to switch to my cell phone hot spot which is not nearly as potent as my Comcast internet is supposed to be. However, my cell phone's hotspot internet connection worked much better and had no issues. I tried plugging directly into my router and restarting my router before my meetings. Please help.