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
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, Big Sur DNS Issue .. these two might be related, but who knows..
So far, only a reboot fixes this...
Any further ideas ?
Best Regards
SH
I'll add my me to to the list. Since Big Sur - but not the original release, not sure which one in particular. Several different DNS related issues:
Cisco AnyConnect client 4.9.04043. DNS is routed through the tunnel. Works great. System sleeps because I walk away, tunnel disconnects. Tunnel reconnects upon wake, DNS resolution is broken. HUP the mDNSResponder and everything is back to normal. This never happens if the laptop doesn't sleep.Safari will randomly have issues with DNS and return NXDOMAIN, even though DNS resolution via dig and ping are working fine. But it doesn't do it with pages that are already cached. Other browsers will work fine when Safari is broken. Need to close Safari and re-open to resolve this issue.See my answer here: https://developer.apple.com/forums/thread/667347?answerId=682255022#682255022