Those other options use Data, so your WiFi and the Data may be in conflict. A way around this is to turn off Data when the WiFi is being used. However, then you 'may' not get messages (through the phones standard messaging) while it is turned off. The text versions may still come through, however anything with images or attachments won't.
It could also be something else on the phone. A bad app, virus, malware.
Lastly, if none of the above help, and if it is still under warranty, contact the manufacturer.