WiFi keeps dropping in Mexico

Thanks for your response. I did look under the WiFi preferences and advanced settings, but I didn't find anything that would prefer the cell network over the WiFi network. I should have also said that last year, I used this same phone while here and never experienced this issue. What changed was that last year, I was using Google Fi and roaming on the Telcel cell network, this year, I'm using T-Mobile and roaming on the Telcel network. I'm also using the same Telmex WiFi as last year. 

Of course, something on my phone may have changed without my knowledge during an update. But the obvious change is that I'm now using a T-Mobile SIM instead of a Google Fi SIM.