I straight up returned my iPhone 18 Pro Max last week. This was infuriating. I was having the baseband lock up and drop to SOS Mode on Verizon, so I got an AT&T eSIM (spent money). Same issue, full loss of connectivity 5 times a day requiring a reboot. So I got a T-Mobile eSIM (spent money). Same issue, full loss of connectivity 5 times a day requiring a reboot.
Then I read online that ONLY the Pro Max uses a Qualcomm modem and the Pro uses Apple C2. My wife's iPhone Air with C2 has great connectivity, better than my 17 Pro Max did before I swapped it for 18.
So I returned the Pro Max, got a Pro, am on T-Mobile full time and my signal strength is good now in buildings that I had 0 or 1 bar before, for years.
Fuck Qualcomm.