iPhone 6 unable to find and connect to wifi networks

Dear ifixit community,

I am having issues with my iPhone 6 wherein it is unable to find my wifi network and connect to it. I have tried:

• DFU mode
• updating to latest iOS
• resetting network settings (which did work one time but a day of use)
• following both these guides (iPhone 6 Wi-Fi Antenna Replacement and iPhone 6 Antenna Flex Cable Replacement ) to replace both the wifi antenna and cable.

Upon restarting the phone, it is sometimes capable of finding the wifi networks but when I enter the password, it states “unable to connect to xyz”, and then I am unable to see those networks anymore.

Has anyone encountered this before and have any advice for me? Because of this I have had to upgrade my data plan significantly due to a lack of wifi; perhaps this is a sign I should purchase a new phone?

Help much appreciated, thank you.