Bt fusion home hub. which is working fine on this computer - however my daughter's remote pc which

Question

which is working fine on this computer - however my daughter's remote pc which is downstairs seems to have 'lost' connection! It was set up as a network and was working fine until yesterday. It is showing as connected, but very slow connection and mozilla firefox won't load... (you are going to have to explain things very slowly guys!) thanks in advance#