My phone won't connect to certain wifi networks?

[AC Question]

My phone, a galaxy s3 won't connect to certain wifi networks even if the signal is strong. Most problematic being school wifi, I can't connect to student or guest wifi but I know that I have the passwords right and it says "saved, secured" When I try connecting it says "connecting..." but never gets to obtaining IP address. I've tried forgetting the network and reentering the password but it still doesn't work. Up till last week it's always worked fine for me. Can someone tell me how to get it to connect please?

 

[B. Diddy]

Welcome to Android Central! Are you able to contact your school's IT department?

Also, make sure your phone's time and date match the school network's time and date exactly.

 

[Rukbat]

Some wifi routers have a problem connecting to some Android phones if they (the routers) are using TKIP encryption. As B. Diddy said, talk to the school's IT department and if they're not aware of that fact, let them know. A simple change to one setting in the router would fix it.

Second possibility: Only a maximum of 253 connections can be made at one time (and the router can be set to allow fewer than that). (IP addresses end in 0-255. 0 and 255 are reserved and 1 is the router itself, leaving 256-3=253.) If there are already 253 people connected, your phone is waiting for someone to disconnect so it can get an IP address, since there are none available.