I bet you are wrong. This is a known issue with 11.4.1.
Google it.
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My error was updating to 11.4.1, which has this known issue of destroying your phone’s wifi.
Or I guess you could say my error was buying an iPhone in the first place.
Out of the 7 iPhones in my house, my phone is the only one not on 11.4.1 (it's on 12). All the other phones (and 4 iPads) are on 11.4.1. None of them have problems with wifi at all.
Sorry you're having issues, but I doubt this is a widespread problem with 11.4.1, otherwise Apple would've released a fix in the two months since it was released.