server does not send proper UTF-8,falling back to local charset connection failed

Hi Team,

We have setup FTP and we are able to login but few customers it was throughing an error as follows

"server does not send proper UTF-8,falling back to local charset connection failed"
Please assist me to resolve the same.
#Log-file information as follows
. 2019-12-16 17:06:10.914 WinSCP Version 5.11.2 (Build 7781) (OS 10.0.17763 - Windows 10 Enterprise)
. 2019-12-16 17:06:10.914 Configuration: HKCU\Software\Martin Prikryl\WinSCP 2\
. 2019-12-16 17:06:10.915 Log level: Debug 1
. 2019-12-16 17:06:10.915 Local account: CORPNET\ThEdUS
. 2019-12-16 17:06:10.915 Working directory: C:\Program Files (x86)\WinSCP
. 2019-12-16 17:06:10.915 Process ID: 13688
. 2019-12-16 17:06:10.915 Command-line: "C:\Program Files (x86)\WinSCP\WinSCP.exe"
. 2019-12-16 17:06:10.915 Time zone: Current: GMT-8, Standard: GMT-8 (Pacific Standard Time), DST: GMT-7 (Pacific Daylight Time), DST Start: 3/10/2019, DST End: 11/3/2019
. 2019-12-16 17:06:10.915 Login time: Monday, December 16, 2019 5:06:10 PM
. 2019-12-16 17:06:10.915 --------------------------------------------------------------------------
. 2019-12-16 17:06:10.915 Session name: username@10.*.*.*(Modified site)
. 2019-12-16 17:06:10.915 Host name: 10.*.*.* (Port: 23)
. 2019-12-16 17:06:10.915 User name: username (Password: Yes, Key file: No, Passphrase: No)
. 2019-12-16 17:06:10.915 Transfer Protocol: FTP
. 2019-12-16 17:06:10.915 Ping type: Dummy, Ping interval: 30 sec; Timeout: 15 sec
. 2019-12-16 17:06:10.915 Disable Nagle: No
. 2019-12-16 17:06:10.915 Proxy: None
. 2019-12-16 17:06:10.915 Send buffer: 262144
. 2019-12-16 17:06:10.916 UTF: Auto
. 2019-12-16 17:06:10.916 FTPS: Explicit TLS/SSL [Client certificate: No]
. 2019-12-16 17:06:10.916 FTP: Passive: Yes [Force IP: Auto]; MLSD: Auto [List all: Auto]; HOST: Auto
. 2019-12-16 17:06:10.916 Session reuse: Yes
. 2019-12-16 17:06:10.916 TLS/SSL versions: TLSv1.2-TLSv1.2
. 2019-12-16 17:06:10.916 Local directory: default, Remote directory: home, Update: Yes, Cache: Yes
. 2019-12-16 17:06:10.916 Cache directory changes: Yes, Permanent: Yes
. 2019-12-16 17:06:10.916 Recycle bin: Delete to: No, Overwritten to: No, Bin path:
. 2019-12-16 17:06:10.916 Timezone offset: 0h 0m
. 2019-12-16 17:06:10.916 --------------------------------------------------------------------------
. 2019-12-16 17:06:10.919 Session upkeep
. 2019-12-16 17:06:10.957 Connecting to 10.*.*.*:23 ...
. 2019-12-16 17:06:10.991 Connected with 10.*.*.*:23, negotiating TLS connection...
. 2019-12-16 17:06:11.060 Server does not send proper UTF-8, falling back to local charset
< 2019-12-16 17:06:11.060 ÿûÿû

< 2019-12-16 17:06:11.060 IFS SupportNet-US, IFS domain username and password required to login.
> 2019-12-16 17:06:11.060 AUTH TLS
> 2019-12-16 17:06:11.060 AUTH SSL
< 2019-12-16 17:06:11.132 Username:
. 2019-12-16 17:06:11.132 Connection failed.
. 2019-12-16 17:06:11.132 Got reply 1004 to the command 1
* 2019-12-16 17:06:11.175 (EFatal) Connection failed.
* 2019-12-16 17:06:11.175 Server does not send proper UTF-8, falling back to local charset
* 2019-12-16 17:06:11.175 Connection failed.

The message is probably not really relevant to the actual problem.
Can you attach a log file from the latest version of WinSCP?