Wi-Fi drops constantly

I had a hub 3 which constantly dropped wi fi all day every day 

engineer came on Tuesday and installed new hub 5 , he said the connection into my home were excellent and all was working well 

one of my devices says it needs moved closer to router , but it works ok , I think  it just doesn’t like the device , 

But … the wi fi is still dropping a few times a day , I can see on my tv box when it does as it flashes and my iPad / phone goes to 5g as no wi fi connection 

customer service says I might need another engineer out , but what would that do , the guy on Tuesday said signals into my home are all good 

virgin outage reports  that intermittent signal in area , but it’s been saying that for months and nothing has been done , even though virgin know about this , it also says no planned works in the area 

any help please , I am slowly going insane trying to sort this out , I just want a functional wi fi service 

Thank you in advance