I’ve a 2017 iMac operating :
System Model: macOS 11.6 (20G165) Kernel Model: Darwin 20.6.0 (Large Sur)
and a 2021 Macbook Professional (M1 Professional)
System Model: macOS 12.01 (20G165) Kernel Model: Darwin 21.1.0 (Monterey)
The iMac is backing up simply fantastic! (solely 20 hours left)

The Samba server is on a Raspberry Pi4 referred to as silver operating Samba 4.8 with a share referred to as TimeMachineBackup
finder from the M1 mac connects utilizing smb://pi@silver/TimeMachineBackup
it then prompts for identify and password – I enter the smb password, it shows a dialog
There was an issue connecting to the server “silver”.
you do not need permission to entry the server

Home windows VMs on each Macs can join okay.
An older 2018 MacBook professional is equally affected

the smb.conf is:

    [global]
   workgroup = WORKGROUP
;   interfaces = 0.0.0.0/8 eth0
;   bind interfaces solely = sure

   log file = /var/log/samba/log.%m
   max log measurement = 1000
   logging = file
   panic motion = /usr/share/samba/panic-action %d
   server function = standalone server
   obey pam restrictions = sure
   unix password sync = sure
   passwd program = /usr/bin/passwd %u
   passwd chat = *Entersnews*spassword:* %nn *Retypesnews*spassword:* %nn *passwordsupdatedssuccessfully* .
   pam password change = no
   map to visitor = unhealthy person
   ntlm auth = sure
min protocol = SMB2
fruit:nfs_aces = no
vfs objects = catia fruit streams_xattr   
fruit:aapl = sure
fruit:metadata = stream
fruit:mannequin = MacSamba
fruit:posix_rename = sure 
fruit:veto_appledouble = no
fruit:wipe_intentionally_left_blank_rfork = sure 
fruit:delete_empty_adfiles = sure 
map to visitor = unhealthy person
highlight = sure
unix extensions = no
browseable = sure
learn solely = no
inherit permissions = sure
;   logon path = %NprofilespercentU
;   logon drive = H:
;   logon script = logon.cmd
; add person script = /usr/sbin/adduser --quiet --disabled-password --gecos "" %u
; add machine script  = /usr/sbin/useradd -g machines -c "%u machine account" -d /var/lib/samba -s /bin/false %u
; add group script = /usr/sbin/addgroup --force-badname %g
;   embrace = /dwelling/samba/and many others/smb.conf.%m
;   idmap config * :              backend = tdb
;   idmap config * :              vary   = 3000-7999
;   idmap config YOURDOMAINHERE : backend = tdb
;   idmap config YOURDOMAINHERE : vary   = 100000-999999
;   template shell = /bin/bash
usershare max shares = 100
   usershare enable friends = sure
[TimeMachineBackup]
path = /mnt/piraid/timemachine
vfs objects = fruit streams_xattr
fruit:time machine = sure
fruit:time machine max measurement = 3T
[homes]
   remark = Dwelling Directories
   browseable = sure
   path = /mnt/piraid/dwelling/%S
   learn solely = no
   create masks = 0775
   listing masks = 0775
   legitimate customers = pi, paddy
;[netlogon]
;   remark = Community Logon Service
;   path = /dwelling/samba/netlogon
;   visitor okay = sure
;   learn solely = sure
;[profiles]
;   remark = Customers profiles
;   path = /dwelling/samba/profiles
;   visitor okay = no
;   browseable = no
;   create masks = 0600
;   listing masks = 0700
[printers]
   remark = All Printers
   browseable = no
   path = /var/spool/samba
   printable = sure
   visitor okay = no
   learn solely = sure
   create masks = 0700
[print$]
   remark = Printer Drivers
   path = /var/lib/samba/printers
   browseable = sure
   learn solely = sure
   visitor okay = no
;   write checklist = root, @lpadmin
root@silver:~# grep -v ^# /and many others/samba/smb.conf
[global]
   workgroup = WORKGROUP
;   interfaces = 0.0.0.0/8 eth0
;   bind interfaces solely = sure

   log file = /var/log/samba/log.%m
   max log measurement = 1000
   logging = file
   panic motion = /usr/share/samba/panic-action %d
   server function = standalone server
   obey pam restrictions = sure
   unix password sync = sure
   passwd program = /usr/bin/passwd %u
   passwd chat = *Entersnews*spassword:* %nn *Retypesnews*spassword:* %nn *passwordsupdatedssuccessfully* .
   pam password change = no
   map to visitor = unhealthy person
   ntlm auth = sure
min protocol = SMB2
fruit:nfs_aces = no
vfs objects = catia fruit streams_xattr   
fruit:aapl = sure
fruit:metadata = stream
fruit:mannequin = MacSamba
fruit:posix_rename = sure 
fruit:veto_appledouble = no
fruit:wipe_intentionally_left_blank_rfork = sure 
fruit:delete_empty_adfiles = sure 
map to visitor = unhealthy person
highlight = sure
unix extensions = no
browseable = sure
learn solely = no
inherit permissions = sure
;   logon path = %NprofilespercentU
;   logon drive = H:
;   logon script = logon.cmd
; add person script = /usr/sbin/adduser --quiet --disabled-password --gecos "" %u
; add machine script  = /usr/sbin/useradd -g machines -c "%u machine account" -d /var/lib/samba -s /bin/false %u
; add group script = /usr/sbin/addgroup --force-badname %g
;   embrace = /dwelling/samba/and many others/smb.conf.%m
;   idmap config * :              backend = tdb
;   idmap config * :              vary   = 3000-7999
;   idmap config YOURDOMAINHERE : backend = tdb
;   idmap config YOURDOMAINHERE : vary   = 100000-999999
;   template shell = /bin/bash
usershare max shares = 100
   usershare enable friends = sure
[TimeMachineBackup]
path = /mnt/piraid/timemachine
vfs objects = fruit streams_xattr
fruit:time machine = sure
fruit:time machine max measurement = 3T
[homes]
   remark = Dwelling Directories
   browseable = sure
   path = /mnt/piraid/dwelling/%S
   learn solely = no
   create masks = 0775
   listing masks = 0775
   legitimate customers = pi, paddy
;[netlogon]
;   remark = Community Logon Service
;   path = /dwelling/samba/netlogon
;   visitor okay = sure
;   learn solely = sure
;[profiles]
;   remark = Customers profiles
;   path = /dwelling/samba/profiles
;   visitor okay = no
;   browseable = no
;   create masks = 0600
;   listing masks = 0700
[printers]
   remark = All Printers
   browseable = no
   path = /var/spool/samba
   printable = sure
   visitor okay = no
   learn solely = sure
   create masks = 0700
[print$]
   remark = Printer Drivers
   path = /var/lib/samba/printers
   browseable = sure
   learn solely = sure
   visitor okay = no
;   write checklist = root, @lpadmin

The iMac is working simply fantastic backing as much as the TimeMachineBackup share as person:pi
The MacBook professional M1 Professional can browse the pi however is not going to hook up with pi’s dwelling or TimeMachineBackup.

How do I diagnose the difficulty of us? (smb logs include no significant messages)