I do not have continuous connection with WiFi

This is particularly true if you have to authenticate with your Wi-Fi network and have "Use Private Wi-Fi Addresses" enabled:

Use private Wi-Fi addresses in iOS 14, iPadOS 14, and watchOS 7 - Apple Support

An explanation from third-party site Eleven software can be found here:

Users with these devices (Apple iPhones running iOS 14 and Apple iPads running iPadOS 14) who have the setting enabled will be forced to reconnect their device via a captive portal every 24 hours. Some users may even be forced to reconnect more often than that if they are leaving and coming back to the Wi-Fi venue. Having to reconnect devices can be a minor inconvenience or a huge pain depending on the use case. 

But only on one network. For that network go to Settings/Wi-Fi and tap on the i next to the network name and turn off Private Address.

Can you please explain? What is happening, are you referring to wi-fi disconnecting at certain times? If not connected to power, the iPhone's wi-fi will disconnect when the screen goes to sleep, but will connect when you open it back up. That is normal behavior.

I don't expect it from any phone either. However, there are a number of questions to ask. Does this happen with all wi-fi networks? How far are you from the router?

That might indicate that the problem is with the university Wi-Fi if it works with other networks. Check with the school IT department. It may have a limit on how long you can remain connected.

Because the network settings are different. It may be signal strength also.