network issues after mojave update

I just installed mojave and all its system updates and I'm having some network connection issues.

These are the symptoms I've confronted with:

• Safari doesn't work (error message: "Safari can't find the server") but other browsers like Chrome and Firefox work just fine
• AppStore can't connect (error message: "Cannot Connect to AppStore) and nothing appears
• In Outlook I can receive mails but I cannot send any (error code 3253). I can sometimes send mails only after many refreshes.
• I installed Cleanmymac X and tried to update apps but Updater doesn't work (Update information not available)
• Tried to install ReImageCleaner but a network error stops the installation.

Thanks!