I need to connect my company server with VT220 via telnet and redis-cli keeps blacked out as soon as I type the command. It looks like escaping character issue. i.e. even when I type "PING" and hit space key, all outputs afterwards are blacked out.

Is there any thing I can fix this issue?
I know ANSI based telnet has no issues at all. but I need to connect with 7-bit VT220.
Please help...