Wifi problem with Macbook Air & iPhone

Hey there, I need help please! My wifi won't work on a MacBook Air and my iPhone after trying to access wifi in a cafe last night. The wifi in the cafe was password protected, I got the password from the staff, when I entered it into the MacBook Air the AirPort symbol started to go from grey to black in waves upwards (instead of reflecting the wifi strength) .. then it went all grey and an explanation mark appeared. Then I tried my iPhone, which appeared to accept the password also but then totally froze on me when I was in Safari. I had to reset my iPhone. I am now back home, where both the MacBook Air and the iPhone normally automatically connect onto the Wifi but neither are working. The MacBook Air is still showing the exclamation mark and the iPhone is generally confused.. as I am! Please help! ta, nat28

Just returned from a 3 week trip with Mac Air and iPhone at my daughters house. Neither would connect to the wireless dsl modem/router. Luckily I had an ASUS repeater device with me and it connected perfectly so I could use my Mac units while I was there.

My sister has an iMac 27" (new) and after two Apple service calls on her setup, they discovered that the new firmware in the iMac won't hook up to older routers with security in them, so my sister is obliged to order a new one.

Seems to be something Mac has caused to happen in the O/S as far as we can tell when trying to hook up to older routers with security features even if you get the password right.