Hello, Since the upgrade to Big Sur, I noticed network issues, regardless which network device is used Wi-Fi, LAN, it does not matter. After some testing the issue is now reproducible as follows: Mount a samba share and copy a file to it, in my case it was PDF file with size of approx. 1.6 MB The copy process does not finish and any samba share is no longer accessible Furthermore DNS resolution no longer works: e.g. executing dig apple.com no longer works, opening any website in any browser just times out, etc. Strangely enough ping apple.com works (...?) If the browser has cached a domain name, the website opens just fine What I tried so far to investigate the issue: I scrolled over the logs in the Console.app .. found nothing Killed the macOS services mDNSResponderHelper, mDNSResponder .. nope Flushed the DNS cache: sudo dscacheutil -flushcache .. nothing Search the WWW for related issues and found these: Big Sur Network Connectivity Issue - https://discussions.apple.com/thread/252037776, Big Sur DNS Issue - https://developer.apple.com/forums/thread/667347 .. these two might be related, but who knows.. So far, only a reboot fixes this... Can anyone else reproduce this issue ? Any further ideas ? Best Regards SH