I reside in an apartment complex where the internet services are not controlled by the management, but instead, they are managed by our ISP, Telcom. Unfortunately, Telcom restricts certain functionalities for users, such as not helping with the opening of ports or providing the admin username/password for my router. Additionally, my router doesn’t appear on the network tab of file explorer. Given this situation, what options do I have to address these limitations to port forward?
The router doesn’t have file shares, so it doesn’t show up on file manager. You most likely need to connect to that with a browser by IP-address. But as port forwarding can have severe security issues I really suggest that you learn more on what you’re trying to do and understand the implications before poking holes to your firewall.
I’m not comfortable to provide step-by-step instructions since doing that wrong can cause all kinds of havoc on your network (and the whole apartment if you happen to have IoT-things around).
I assure that I have researched this for a long time and that I know how to protect this open port.
The fact that you said “my router doesn’t appear on file explorer” tells us everything we need to know about your skill level. You don’t know the first thing about “protecting this open port” and you aren’t qualified to assess the security risks of what you are trying to do.