Unable to try Ethernet cable etc. as he is in a relative's house whilst they are away.
Sorry, I don't follow why he can't use an ethernet cable?
Maybe his laptop doesn't support the wireless encryption method used by the router. Can he login to the routers web interface and have a look at the settings?
Being that he is not at his own house, but at a relative's whose also away, he does not have an ethernet cable to try or intefere with the router settings as if it was his own. In any case he is not computer savy and login to the router web interface would be a step too far for him!
So it may be, as you say that his laptop doesn't support the wireless encryption method used by the router, in which case he will have to do without internet whilst he is away!