Wildly fluctuating speed test speeds

Hi, hoping for some assistance. I’m at my wits end with my Wi-Fi. Two year saga. I’m supposed to get 1.2 GB of speed and my speed tests give me everything ranging from 30 MB to 1100. This all equates to at times slow loading emails, webpages that struggle to open, streaming content like Netflix, and Hulu booting me off or getting stuck, and glitchy zooms.Last time I changed the modem about six months ago and it temporarily fixed it - but it’s happening again.

I’ve had the line from the pole to my house changed. I’ve had tech come and change the fittings outside. Everyone from Xfinity on their end says the signal “looks great.” The app says “your wifi is booming!” I had my modem reprovisioned, whatever that means. I even had an electrician change the coax that goes from my outside my house up into my modem.

Yesterday I finally had another tech come and change the modem one more time. Didn’t solve it. Impossible to reach anybody who doesn’t want to just send a signal refresh. The tech at my house said, “I don’t know what to tell you if this new modem doesn’t fix it. The best I can do is tell my supervisor and they’ll try to send a truck and check things out on the street.” No other info. Even in the Xfinity store they said “we don’t know what to tell you.” I have an appointment to have FiOS Wi-Fi installed next Wednesday, but that’s my last resort because I have everything bundled with Xfinity and that that will wreak havoc. Please help! Not sure who to contact anymore.