2. Is there something wrong with your computer settings? Check whether the IPV4 address is automatically obtained, etc. The best way is to take your computer to a port where you can surf the Internet and see if you can surf the Internet.
3. Excluding the above reasons, it can only be a school network problem. Recently, the school network seems to be very unstable, and IP addresses are often unavailable. Let's go to the current teaching center to respond.