I think you can. I routinely have 3 or so on my home box, and at my office we can have up to 10. It only really depends on what your computer can handle.
There are settings in sshd_config that you may have to change. Here's a link to the man page. It is found in
/etc/ssh/sshd_config. Default is 10. You'll need to increase this.
I found this resource that talked about how to increase the maximum. Here's a little explanation:
/proc/sys/net/core/somaxconn- maximum TCP connections (SSH connects over TCP)
/proc/sys/net/core/netdev_max_backlog- not as big of a deal, this is the max packet queue
You can just edit these numbers if you need to increase it. My default
somaxconn is 128, so you should be good.
Use websockets with NodeJS.
This should get you started. If you don't want to learn how to use websockets, just send HTTP Post requests to a webserver. They don't have too much overhead and you can send a lot of data this way. I would personally opt for the websockets because they're real-time and are not too difficult to set up.