Edit: I'm soo sorry this post is really a mess now. Please read the context in grey to understand.

Hello I disabled DHCP on the MR600 and now all of my devices use the Apartment internet Wifi !
Thanks to this post https://community.tp-link.com/en/home/forum/topic/201144 and this page 4.2. Use the 4G LTE Router as a DHCP Server

On windows I used "Allow other network users to connect through this computer's connection" option on my Wifi with the ethernet port selected.

Windows file sharing between PC and Phone is working !
BUT in order to make Philips hue bridge IN LOCAL, I had to make my Windows 10 PC network a private network instead of a Public one...
(I can see their printers, and they can see my PC and Hue bridge, but they shouldn't be able to control them in any way. They can go in my Wamp server if it's online...)

I can no longer access to the MR600. (Even by tplinkmodem.net and/or disconnecting from the apartment wifi.
My phone connected to the wifi of the MR600 is telling me the current gateway IP, which is actually the IPv4 adress of my ethernet port on my PC)
MR600 is linked to my PC via a LAN port (Just tried the WAN port and it didn't allow the internet from my PC, and Phone couldn't connect to MR600 as it can't asign an IP with DHCP disabled)
But now I want to access my PC file through internet as a NAS, and I need to access it.
How do I access my MR600 back ?
Should I reset it and make an account to use the dashboard of the MR600 online ?

Please don't forget and consider the risks of using non secured wifi.

(Just in case, what should I and others be aware of by doing this ?)
Thank you !

Original post to understand what lead me in this situation:
Title: How to make appartement wifi <> windows 10 wifi <> windows 10 ethernet <> MR 600 access point/LAN

Hi, I have some trouble doing the following:

apartment wifi <> windows 10 wifi <> windows 10 ethernet <> MR 600 access point/LAN

Context:
My apartment has an internet connection which is better than 4G signal, but it's by Wifi only (No password wifi and shared between residents through a portal with login credentials...)
I can't login to the apartment access point wifi with more than one device at the same time.

I use 4G LTE with the MR600 to make a personal LAN, but the internet speed is 10x worse.

I would like to use my desktop windows 10 PC like this:
Take and use the Wifi of the apartment.
Share this internet connection via ethernet into the WAN port of the MR600.

Pros:
10 times faster internet, and saving money by not paying for 4G.
Cons:
People can snitch what websites I browse, but HTTPS should be safe for payements and credentials.

Ideally, the MR600 would be connected to the wifi apartment access point (as WAN)
and provide LAN through its ethernet and own wifi.
(But from what I understand, it can't do that.
I have also a TP-Link RE450 but it can't use an existing wifi and provide LAN with custom wifi password which I need)

What I tried:
I  changed the MR600 mode to wireless access point instead of 4G router, and disabled 4G internet from it.
I tried doing bridge connection on my PC between Wifi and ethernet, and the "Allow other network users to connect through this computer's connection" option on my Wifi with the ethernet port selected.

When doing ether of them, (PC Wifi connected to apartment access point, and PC connected to the WAN port of MR600)
my PC is trying to get internet from the MR600 and not the apartment access point. This results in no internet at all.

Also:
Both the MR600 and Router of the apartment use the same default IP address => http://192.168.1.1/
Use http://tplinkmodem.net/ as a workaround

I use the windows file sharing and ES explorer app on android to access shared folders of my PC from my phone.
I would like to keep doing that.

My PC has two ethernet ports (1Gb and 2.5Gb).
I could do this, which looks horrendous, in order to keep my file sharing ?

MR600 V2 (1.5.0 0.9.1 v0001.0 Build 210914 Rel.59719n)
Windows 10 Pro

Thank you for taking the time to read all of this and helping me :)