You could leave this app as is and use is as a WiFi extender or 'MQTT-like' server in your network but you can also extend it because it does not use that much memory.

Install 'NTP' by Stefan Staub, 'ESPAsyncTCP' by dvarrel and 'ESP Async WebServer' by Me-No-Dev via the library manager.
Note the spaces in the name 'ESP Async WebServer'

ESP8266-Servers has servers like:

• LittleFS Web (upload, download, copy, rename, create, edit etc.)
• Router with NAPT and Reverse NAT
• WebSockets server with example clients (GPIO and DataStore like MQTT)
• and a Configuration Manager

Other functionality includes:

• FOTA (my implementation of 'Firmware On The Air' which you can customize)
• NTP
• Symmetric encryption of stored credentials

Before the details and since there are many license types out there (kindly meant)....

• As long as you keep this notice with this app you are licensed to do anything legal you want to do with it

Every now and then you may want to have a look at the screenshots at the end of this page

First use the green 'Code' button on https://github.com/JackV2020/ESP8266-Server to download the zip file

Extract that zip folder in your Arduino IDE Sketchbook folder and name the folder ESP8266-Server

• It is modular, every server part has its own tab(s) in Arduino IDE

  • Makes it is easy to copy and use parts in other apps
  • Every tab has more detailed info in its header
    • what is it for and how to get it running
    • which libraries does it use and how to get these
    • etc.
  • ESP8266-Servers.ino integrates the parts into one ready to use app

• Configuration Manager to manage setting

  • The initial installation has no settings but provides an access point
    • WiFi SSID 'Setup 192.168.4.1 1234567890'
    • Use your laptop/phone/tablet/... to connect to to this WiFi SSID
    • Logon with password 1234567890 and browse to 192.168.4.1
  • On the home page you click Configure
  • Click the Info button and read what's there (click again to hide)
  • Fill in the fields you want to change
    • Make sure that the 'Network NAPT' does not match your home WiFi
  • Fill in the password in the bottom field (initial 'secret')
  • Click 'Save' and wait for the count down to finish
  • Use your laptop/phone/tablet to find the new SSID
  • The new WiFi SSID contains:
    • the SSID name you gave in
    • and the hostname and the IP it has on your home WiFi
  • Now you can
    • connect to your home WiFi and browse to that IP address
      • OR
    • connect to the new WiFi SSID, logon and
      • browse to 192.168.'Network NAPT'.1 like 192.168.7.1

• LittleFSWeb to manage the LittleFS file system on a web page

  • Access your device via your home WiFi or the NAPT network
  • On the home page you click LittleFSWeb
  • Logon (initial 'admin' 'admin', maybe you changed it already)
  • Click the Info button and read what's there
    • Create new files and (subdirectories)
    • Select a folder and upload files
    • Download files
    • Rename and delete a file or directory(tree)
    • Edit files in web based editor
    • and more

• NAPT_RNAT implements a simple router

  • NAPT for 4 clients
  • DHCP reservations template file which can be editted with LittleFSWeb
  • Web page showing IP, MAC and name of connected NAPT clients
  • Reverse NAT to access clients from 'outside'
  • Reverse NAT template file which can be editted with LittleFSWeb

• Websocket server with 2 applications

  • html and .ino websocket client examples are available in LittleFSWeb
  • Control 6 GPIOs, react on interrupts of 5 GPIO's and receive A0 reading
  • wsDataStore to share data between clients in a sort of 'MQTT-like-way'
    • you can share data between clients on NAPT and WiFi side without RNAT
    • the app itself can also share in wsDataStore (see NTP client)

• NTP client:

  • The internal clock is synchronised with ntp
  • Has functions to give you boottime, uptime and current time in your app
  • puts 'BootTime' in wsDataStore for demo purpose

• FOTA, 'Firmware Over The Air' allows you to upload sketches remotely

  • No need to connect to your computer when you have an upgrade

• Examples and templates

  • Some files are created after startup but only when they do not exist
  • When you wreck one, delete it, reboot and the default is recreated
  • Template for ntp configuration (Summer and winter time)
  • Template for DHCP reservations on NAPT subnet
  • Template for Reverse NAT
  • /zExamples folder with 4 websocket client examples
    • html to share data with other clients (already shows BootTime)
    • ino to share data with other clients (also with html clients)
    • another ino to share data with other clients (also with html clients)
    • html to control GPIOs, react on interrupt and receive A0 readings
    • and proc_processor.html.proc for the proc_processor (see below)
  • /index.html is also a template you can edit and delete
  • /LittleFSWeb/LittleFSWeb.html is the LittleFSWeb page you may change
    • be carefull with this one
    • when you wreck it use http://'YourESP8266DeviceIP'/LittleFSWebFixIt (this serves the original page directly from PROGMEM)

• The main webserver

  • Has a function in it so it can replace strings in your html, css and js files with other strings
    • See the proc_processor.html.proc example in /zExamples for that
    • Note the extra file extension .proc to trigger the replacing
  • Also serves a json page with information you may be interested in like heap info, network and time details
  • Prefers to serve gzip files so it soes not have to send that much
    • Try the next :
      • Upload LittleFSWeb.html.gz to /LittleFSWeb (from LittleFSWeb_html_gz)
    • OR if you made changes to /LittleFSWeb/LittleFSWeb.html
      • Download /LittleFSWeb/LittleFSWeb.html
      • On your computer gzip (with for example 'gzip -k LittleFSWeb.html')
      • Select the folder /LittleFSWeb
      • Upload '/LittleFSWeb/LittleFSWeb.html.gz'
    • AND
      • Edit /LittleFSWeb/LittleFSWeb.html, clear it and save it
      • Now you have more space and LittleFSWeb page may start faster

NOTES:

• I use Wemos D1 mini Pro and suppose this works on other ESP8266 devices

• To use the memory efficiently the wsDataStore is in 2nd Heap and MMU setting needs to be option 3 to enable wsDataStore:

  • "16KB cache + 48KB IRAM and 2nd Heap (shared)"
  • this also gives you more code memory

• You may tune:

  • SERIAL_PRINT in ESP8266-Servers.ino to enable/disable printing to Serial
  • DEFAULT_MAX_WS_CLIENTS in ESP8266-Servers.ino to change the number of web socket clients
  • chunkSize in LittleFSWeb.h where the file is saved in chunks to allow parallel activities
  • IP_NAPT_VALUE and IP_PORTMAP_VALUE in NAPT_RNAT.ino control the table sizes and are very memory consuming
  • wsDSNumRows in wsServer.ino to set the number of entries in the wsDataStore
  • an anything else you can find and want to

• You can use the web server for other things like

  • Create a folder /games
  • Upload all files in the project subfolder games to this new /games folder
  • Close all your browser windows
  • Start a browser to http://'YourESP8266DeviceIP'/games/index.html
  • Note that you can play the games without the need to logon to LittleFSWeb

• Did you lock yourself out in a terrible way ?

  • Connect D8 to the 3.3V while it runs which
    • deletes files with user and password
    • deletes /index.html and LittleFSWeb.html
    • deletes /index.gz and LittleFSWeb.gz
    • reboots
    • and you have default access again
    • all other files are still in place

The first is the home page with access to other pages.
The Configuration Manager to enter settings.
The main screen of LittleFSWeb.
Note the Info buttons which explain more.

The editor window with resize buttons for the font. Resize the text area on your computer using the little triangle in the bottom right corner and use 2 fingers on your mobile mobile. In the text area you can use ctrl-s to save and tab to enter 2 spaces.
The NAPT overview with my phone as client. (2nd row in DHCPReservations.txt so address 101)
The json page. You find that the napt_IP 192.168.0.1 has the 0 from the Configuration Manager page.
You also find the my phone as NAPT client and my laptop 192.168.2.27 running 2 websocket clients.
I just rebooted so the uptime is just 43 seconds.

Two screenshots of the html websocket clients
You can start more than 1 instance of each and see they are in sync.
As soon as you add a value in the datastore it is there in the other window.
You can also use the ino example for the datastore which prints info on the console.