How To Access And Open Yet Blocked Network

My local coffee shop has free internet and it is open requiring no password. I can connect to it but it won't transfer any data. The owner said he had to check something on my computer and did and it worked. Now I want to use another computer and my phone on the network while I am in there but don't want to hand my stuff over to him. What exactly is he changing which allows my computer to accept his signal?

 

It depends what you want to do on a free wifi spot. If it is more than web surfing and sending/receiving emails, it may not be allowed or may have some inbuilt limits. You need to talk to them about it, but NEVER let them access your system.