Connection

Hi

I hope someone can offer some help please. I have checked on the dashboard and it shows that my area has got 4G ....fantastic, you may think,  but why, as soon as I go more than 200 yards from home do  have no signal? I missed a really important call a couple of days ago, but I cannot stay at home all the time.  I never got a message to say my Samsung phone is no longer compatible. I have checked that roaming is turned on and that stays on  even when I have lost the connection. In very simple terms,  can someone please tell me what is wrong or should I just change to another provider, because sadly, currently, the way things are is not acceptable.

Thank you in anticipation of a straight forward, jargon free reply.  : )