We have a debian buster booting into multi-user.target (enabled via sudo systemctl set-default multi-user.target) and a USB serial adapter. Loggin in and accessing serial console via
sudo screen /dev/ttyUSB0 9600
for configuring Cisco Switch works fine.
However when I connect to this machine via ssh and then execute within the ssh session command from above it won't work. In putty as ssh client I see no output at all. I have to pull and reconnect serial USB adapter to make it usable again. Connecting with MobaXterm works only partly. Some inputs are completely ignored, outputs is often crippled like wrong position or even missing a lot characters. I've tried already minicom. Same behaviour. When connected via ssh you can't even quit it anymore. In screen CTRL+A and CTRL+D work at least.
What piece am I missing to access cisco serial console over ssh?
EDIT: Made some more tests: Tried to ssh from another Linux machine --> works With putty executing show run for getting the configuration and then hitting space key to see the next lines, it works a few times hitting space key, but still some lines are missing or at the wrong place. Then it hangs completely. Closing and re-opeing screen doesn't work.
Another point: Accessing a linux machine over MobaXTerm ssh and then connecting from there via ssh gives the same problematic behaviour. With crippled output it looks like
p power inline never speed 100 duplex full arp spanning-tge service-policy output Qos1234 ! interface GigabitEthernet1/10