I tried to search on google but it seems SSH flashing doesn't exist.
Have you tried to replace a new Ethernet cable first? and maybe your cable is broken or the ethernet socket full of dust and dirt. Make sure both cable and ethernet socket is clean.
Well, your final solution is the SD card this is the only final solution that may solve this issue.
If you don't know how to do this you can follow the guide from here
T9+ Control Board Program Recovery.