HTAccess Rewrite Issues - php

Question

I am writing a website which is dynamically populated through an Oracle database.
I have completed the desktop site and am now required to create a mobile site. Due to how different the sites are planned to look, I have opted to create 2 different "template" like websites for the mobile and desktop sites.
However, for my desktop site, everything is built off the index.php file in order to allow it to be completely dynamic. Pages are therefore look like www.domain.com/index.php/page in the url.
For the desktop site, this works. I am using a generic index.php removal rewrite rule in order to then make the url www.domain.com/page however still display the same page as the previous URL.
My issue, is that now I have a www.domain.com/mobile/index.php. Which has been created and for the most part has been working, however when trying to add addition dynamic pages to the mobile site. www.domain.com/mobile/index.php/about for example just redirects to www.domain.com/mobile/ and it doesn't even include the about part of the URL.
After much debugging, I have discovered it is definitely the .htaccess that is causing the issue.
If you have any insight into my issue, please help me out.
Thanks in advance
EDIT 1
Rewrite Rules are as follows
# Removes index.php from ExpressionEngine URLs
RewriteCond %{THE_REQUEST} ^GET.*index\.php [NC]
RewriteCond %{REQUEST_URI} !/system/.* [NC]
RewriteRule (.*?)index\.php/*(.*) /$1$2 [R=301,NE,L]
# Directs all EE web requests through the site index file
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /index.php/$1 [L]

Answer 1

You can use this code in your /mobile/.htaccess file:
DirectoryIndex index.php
RewriteEngine On
RewriteBase /mobile/
RewriteCond %{THE_REQUEST} /index\.php [NC]
RewriteRule ^index\.php(?:/(.*))?$ $1 [L,R=302,NC,NE]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.+)$ index.php/$1 [L]
This will override all the rules present in parent .htaccess for /mobile/ URI path.
Simplified version to make it work in root .htaccess:
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^(mobile)/(.*)$ $1/index.php/$2 [L,NC]
# Directs all EE web requests through the site index file
RewriteRule ^(.*)$ /index.php/$1 [L]

Answer 2

Based on the debugging you mentioned, there is a rule in your .htaccess which is rewriting www.domain.com/mobile/index.php/about to www.domain.com/mobile/. So, if you find which rule this is, you can add one above it that will catch requested URLs for your mobile pages and then not allow the problematic following rule to run. Something like this:
RewriteRule ^mobile/index.php/([a-zA-Z0-9-_]+)$ ^mobile/index.php/$1 [L,QSA]
The L ensures that if the user's request matches this rule, no further rules (including the one causing the issue) will be executed.

Answer 3

Thank you for the answers you've both given, however neither of them worked, I've now solved the issue, it was to do with the final RewriteRule at the end
# Directs all EE web requests through the site index file
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /index.php/$1 [L]
I needed to change it to
# Directs all EE web requests through the site index file
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} !/mobile/.* [NC]
RewriteRule ^(.*)$ /index.php/$1 [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} /mobile/.* [NC]
RewriteRule ^(.*)$ mobile/index.php/$1 [L]
So that it would work with both mobile and desktop sites.