How to backup with tftp command

I tried to backup ucs file with tftp command.

But the command was timeout and file size was 0 byte.

I also see this doc(https://support.f5.com/csp/article/K93412415), but I use mgmt IF.

Can I use tftp command on LTM ?

( scp command is work. )

There are no ACL between LTM and TFTP server.

environment

BIG-IP LTM virtual edition (on AWS)

16.0.1.1 build 0.0.6

Regards,