Frequent Drops in Connection

This thread is marked as solved - but there is no visible solution ( that I can see ) - 

did the visit from the engineer help ? 
what did they do ?

Been having this WIFI dropout problem- for years - as are a neighbour here, and a friend who lives other side of the city, and also a VM customer.

Wired equipment works fine, but WiFi connected gear drops out frequently. IPhones, Android, it doesn’t matter, they all drop out regularly. A nuisance, and particularly on WiFi connected security devices. 

Usually