Unstable Connection

I'm using T-Mobile Home Internet Plus, and the speeds are great, and it came with an access point, which covers most of my home with a good signal. However, there are times where some of the devices seem like they're too far away, and the signal drops out. I'm in online classes over Zoom, and at least three times during class it will lag, and I'll lose part of the conversation and then Zoom will tell me that my Internet connection is unstable. This also happens on Xbox LIVE a lot, to the point where I can't even stay in a party with someone without constantly getting disconnected. I usually keep about three bars, which a T-Mobile representative told me was normal. When I called about the unstable connection, they told me they were doing maintenance on a local tower, which required a "part" that had to be ordered, and this was a month ago, and I'm still having the same issue. Is there any way I can fix this, or do I have to just deal with it? Thanks in advance for the responses