I have the same issue. SMB connection from Monterey 12.0.1 is not working with my Synology NAS. However, forcing Monterey to use SMB2 allowed me to get a connection (https://stadt-bremerhaven.de/avm-fritzbox-smb-problem-mit-macos-12-monterey-und-wie-man-es-behebt/).
chrisrom
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