Internet Keeps Dropping

I've been having a connection issue for more than a year, but recently it's become really problematic because my wife and my children are working and doing school from home. We tried buying our own modem hoping this might solve our issue, but we continue to have moments of dropped internet. That's a huge issue. Especially when my children are in the middle of a class zoom meeting. We have had multiple phone calls with customer service. We have had a tech out to look to see if anything was loose or poorly wired. We are not getting better and we really need help.