can anyone educate me more about computer networking as a career?
Routers , protocols , network towers, 4g/5g , internet, firewalls, wired/wireless etc , these must be part of some kind of decent job i guess? (I mean there are those guys who just know how to install these in people's systems and then there are guys who are researching and learning about these systems).

- What is the job opportunity? how and when can we start a career there?
- How difficult it is to reach telecom giants like cisco, at&t , airtel, google fiber etc ?
- How interesting is the work there?
- what programming knowledge should we know or we will be learning about?
- How stable is the career there?

Also, is there a masters in it?

I can say about one of those companies, one project: low lvl c,embedded, programming. Some sort of rtos is involved for sure.
So, I guess rtos and basic concepts like data structures, algos and pointers are a way to start. I always recommend kernighan and ritchie c, idk for rtos.
Any embedded c job could lead you there.
It depends on you how interesting it will be for you, and on your teammates. First one you can experience during learning and decide if it's for you. Teammates you can't predict.
Career is very stable, it's been around since there was programming, as oposed to javascript.

I agree with the other comment. That said, I don't know that I would be interested in working for Cisco, Alcatel and any of the big telcos. They're notoriously fickle and prone to bottom-line oriented attrition. The work you will get will be corporate drudgery. The era of the network admin as career has passed (though it doesn't sound like that's what you're after), the jobs that haven't already been outsourced will be automated before too much longer.

What I will say in regards to networking, and somewhat reflecting the other answer is that the really cool/interesting trending growth areas that are emerging are in the cloud with things like FPGA-based networks and SDNs.

Definitely learn to code if you want a stable career in networking (rust, go, erlang, c). Focus on systems engineering.

Re degree: Systems engineering undergrad is good with minor in EE. Masters in the same or CS.