Is it normal that this laptop doesnt work

Is it normal that this laptop has now been changed from one that needed connected from the euthernet cable to one that uses wifi. It worked just fine the first day l used it when l got it back with some dificulties that stopped eventually. But now its back to not working. It'll connect to the network then stop. Then i'll get some messages saying cannot find certificate to log onto networks but there was never a certificate to use it. But then again it never said that. Also I could have a strong wifi connection & then it says no signal, then connected then low signal then not. So Then l Tried things the internet said on my home computer that l could try on my laptop& that was a fail cuz l am dumb when it comes to that & couldnt find anything. & it will connect sometimes but then'll lose signal & when l use it now it says server requested timeout & l'm like really?! This has been happenin everytime l get the internet to work. & its making me mad. anyone think they could help? MAYBE l messed it up some how?