So I just started watching Eli The Computer Guy's videos on networking and I really like them so far(only on the introduction so far though), but I was a bit confused about some of the stuff and I thought to myself that some of this might be obsolote or not so much in use these days/different. So here are some questions(now bear with me, I'm still a noob to the whole topic of networking):

-Are Eli's videos on networking obsolete(besides the speeds that he talks about), what you recommend some other tutorial, if so which one?

-Is a switch necessary for a small network?

-Do we still connect routers to modems or do we just use what we refer to as a router(a mix between a router and a modem -> gateway/gateway router)?

-Can you connect an ethernet cable to your router/gateway?

-So according to Eli if you have multiple routers they make seperate networks that cant just be acessed from each other, then how come it be that I can access my rasperry pi when I'm connected on the network of one router when the raspberry pi is connected to the network of another router and how come it be that once you have the wifi password you can connect to all of them?

Okay I give up. I just don't get this docker networking stuff. I need someone to save me these sleepless nights and get on a call with me. A docker expert please. I am dying and my make believe devops engineer persona is crashing on me.

I was trying to set up my own "cloud" for iot experiments. I planned to use Intel Edison with mqtt broker (using mosca) and a node js app for providing API for mobiles and browser. And also to do other book keeping.

I spent the half day trying figure how to expose these servers to internet.

I configured ddns in noip.com and ddns settings configured to it in my router.
Port forwarded to the local server services I needed.

And then tested. Worked perfectly on any device in my router connected network. Tested on mobile network. Bam! It fucking doesn't work.

Then connected another router.
Double port forwarded. Again worked perfectly on router network. And failed on mobile.
Tested if ddns is right. Did nslookup it was fine as fuck.
Then disabled port forwarding. Did dmz. Nope. Nadda. No luck.

Then scratched my head so hard that I lost more already losing hairs.

Then remembered about router hardware firewall. Disabled it.
Tested
And there it didn't work.
My dreams shattered like a fucking deer hit by car on highway.
Didn't work.
Then I see the IP pointing to my router in nslookup. Its 172.20.xx.xx. Its a fucking private IP.

My Asshole ISP is running another private network behind firewall. Which I fucking can't port forward
Now I think how much of a noob and idiot I am. Fuck this shit. Fuck all of these shit.
I am going for SaaS option for mqtt broker.
(Or help me?)
Once again.
Asshole ISP.
Fuck your firewall.
(PS: I had test the next day. FML)