Failed MacOS file sharing using wrong user account - how to reset? I have two Macbook Pros:

Mac1 is 16' 2019 running Big Sur 11.2.3
Mac2 is 13' 2017 running Catalina 10.15.7.

I am encountering this weird problem while trying to access file on Mac1 from Mac2 via MacOS's File Sharing. In Mac2's Finder, I use smb://Mac1 to open Mac1, but although occasionally it is successful, most of the time it just times out before popping up saying 'connection failed'. However, I can open Mac1 from my iPad very easily. So I guess something wrong on Mac2.
I checked sys logs in Console app and found something maybe relevant:
KernelEventAgent   tid 657c52ee type 'smbfs', mounted on '/Volumes/mac1', from '//ABCD@ufo20mbp._smb._tcp.local/mac1', not responding
KernelEventAgent   tid 657c52ee type 'smbfs', mounted on '/Volumes/mac1', from '//ABCD@ufo20mbp._smb._tcp.local/mac1', dead

in which ABCD IS NOT the correct account name to login on Mac1. I highly believe this could be the reason why the connection fails, but I cannot find any place to reset the account name. I am not sure if I am correct but I tried smb://XYZ@mac1 in Finder, but no luck, in which XYZ is the right login account name on Mac1.
Please advice what I should be to fix this issue.
Network share credentials are stored in Keychain Access.app. Take a look there. You may search for ABCD to quickly find any credentials containing this login. You can then just delete the wrong items.
Please note, when using ⌘ K in Finder, your connection string needs to look like this:
smb://&lt;ip address&gt; e.g. smb://192.168.0.123
or
smb://&lt;local hostname&gt; e.g. smb://targetMacName.local (how to find/change local hostname)