Issues connecting to internet on my refurbished iPhone

Hi!

I have an Iphone XR and since a acouple of days some of my apps such as Youtube, Messenger and Whatsapp have been having issues connecting to internet even though I have called my network provider and there is no problem on that end. I can browse on safari just fine, same goes for Facebook, Instagram etc... however whatsapp just doesn't seem to connect, youtube loads the home screen just fine and the suggested videos when clicking on a video but not the video in itself, and messenger allows me to receive messages but not send them. Or with a minimum of two hour delay.

Also I am having issues connecting to the wifi. It says it is connected but I am always on mobile data and if I switch it off, nothing. Even though my computor and the rest of the family have no issues.

My Iphone is refurbished, can that be the cause? It was almost new though. I have done everything.

Thank you

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