Oh my god thanks I'm not alone   I come to the end that the smb driver is buggy. I installed a clean version of Big Sur, smb server shows, it connects, for some files (drag and drop) it gives error -8084. I tried also to zeroes the free space on the disk where the share is, as suggested somewhere, no change. When I copy from terminal I get a kernel panic, for example: panic(cpu 5 caller 0xffffff80080bf424): "Zone element 0xffffff9379602a00 was modified after free fo