Garbage characters when using serial connection over SSH connection with minicom/screen

I have a serial connection made with /dev/ttyUSB0 locally from my laptop to a cisco lab router and using minicom/putty/screen all work fine locally (hardware control: on, software control: off, 9600 8N1). When I'm at work I SSH into my laptop at home, which works fine, but when I use minicom/screen to use the lab router I get garbage characters. I tried SSHing at home from another machine and it worked fine initially, but then later it started having garbage characters. Since this is only happening over an SSH connection, what could be causing this? Any setting changes that could fix this?