I have found a couple apps that refuse to open on my home wifi. They will work on the wifi i have at work and they will work using cellular data. I've tried turning off wifi and back on, rebooting the phone, forgetting the wifi network and re-joining. last night i put my phone in airplane mode for a minute and switched back and it decided to work but only for a short time and then the problem came back. i restored my iphone 6 from backup when i first set it up. i don't know if resetting the network settings will work or not. i don't know what to do.