Been there, the problem in my case was that the FKU app flashed the CAF version and I have a OOS based Rom. Switching to the correct version brought back my wifi.I'm in the exact same situation with multiple wifi disconnects today and yesterday.
I didn't change anything else recently than the kernel, so I can't think of another reason..but I always read in this thread that the kernel doesn't change any wifi settings.
Edit: I'll reflash 43 and check if that changes anything. Atm I can't even connect to WiFi without restarting my phone.
Just my five cents