Форум phpBB в подпапке /forum/ рядом с Opencart — как отделить?

Есть сайт на опенкарте, в подпапку /forum/ установил phpBB форум
При выполнении некоторых запросов перекидывает на страницу 404 опенкарта
Как исправить? Чтобы опенкарт не лез к phpBB
На поддомен выносить не хочу, понимаю что нужно настроить .htaccess опенкарта и phpBB, но что именно - не знаю
У меня shared hosting от namecheap, с управлением cPanel

.htaccess опенкарта:

# 1.To use URL Alias you need to be running apache with mod_rewrite enabled.

# 2. In your opencart directory rename htaccess.txt to .htaccess.

# For any support issues please visit: http://www.opencart.com

Options +FollowSymlinks

# Prevent Directoy listing
Options -Indexes

# Prevent Direct Access to files
<FilesMatch "(?i)((\.tpl|.twig|\.ini|\.log|(?<!robots)\.txt))">
 Require all denied
## For apache 2.2 and older, replace "Require all denied" with these two lines :
# Order deny,allow
# Deny from all
</FilesMatch>

# SEO URL Settings
RewriteEngine On
# If your opencart installation does not run on the main web folder make sure you folder it does run in ie. / becomes /shop/

RewriteBase /
RewriteRule ^sitemap.xml$ index.php?route=extension/feed/google_sitemap [L]
RewriteRule ^googlebase.xml$ index.php?route=extension/feed/google_base [L]
RewriteRule ^system/storage/(.*) index.php?route=error/not_found [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} !.*\.(ico|gif|jpg|jpeg|png|js|css)
RewriteRule ^([^?]*) index.php?_route_=$1 [L,QSA]

### Additional Settings that may need to be enabled for some servers
### Uncomment the commands by removing the # sign in front of it.
### If you get an "Internal Server Error 500" after enabling any of the following settings, restore the # as this means your host doesn't allow that.

# 1. If your cart only allows you to add one item at a time, it is possible register_globals is on. This may work to disable it:
# php_flag register_globals off

# 2. If your cart has magic quotes enabled, This may work to disable it:
# php_flag magic_quotes_gpc Off

# 3. Set max upload file size. Most hosts will limit this and not allow it to be overridden but you can try
# php_value upload_max_filesize 999M

# 4. set max post size. uncomment this line if you have a lot of product options or are getting errors where forms are not saving all fields
# php_value post_max_size 999M

# 5. set max time script can take. uncomment this line if you have a lot of product options or are getting errors where forms are not saving all fields
# php_value max_execution_time 200

# 6. set max time for input to be recieved. Uncomment this line if you have a lot of product options or are getting errors where forms are not saving all fields
# php_value max_input_time 200

# 7. disable open_basedir limitations
# php_admin_value open_basedir none

.htaccess phpBB

<IfModule mod_rewrite.c>
RewriteEngine on

#
# Uncomment the statement below if URL rewriting doesn't
# work properly. If you installed phpBB in a subdirectory
# of your site, properly set the argument for the statement.
# e.g.: if your domain is test.com and you installed phpBB
# in http://www.test.com/phpBB/index.php you have to set
# the statement RewriteBase /phpBB/
#

RewriteBase /forum/

#
# Uncomment the statement below if you want to make use of
# HTTP authentication and it does not already work.
# This could be required if you are for example using PHP via Apache CGI.
#
#RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization},L]

#
# The following 3 lines will rewrite URLs passed through the front controller
# to not require app.php in the actual URL. In other words, a controller is
# by default accessed at /app.php/my/controller, but can also be accessed at
# /my/controller
#
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ app.php [QSA,L]

#
# If symbolic links are not already being followed,
# uncomment the line below.
# http://anothersysadmin.wordpress.com/2008/06/10/mod_rewrite-forbidden-403-with-apache-228/
#
#Options +FollowSymLinks
</IfModule>

# Apache content negotation tries to interpret non-existent paths as files if
# MultiViews is enabled. This will however cause issues with paths containg
# dots, e.g. for the cron tasks
<IfModule mod_negotiation.c>
	Options -MultiViews
</IfModule>

# With Apache 2.4 the "Order, Deny" syntax has been deprecated and moved from
# module mod_authz_host to a new module called mod_access_compat (which may be
# disabled) and a new "Require" syntax has been introduced to mod_authz_host.
# We could just conditionally provide both versions, but unfortunately Apache
# does not explicitly tell us its version if the module mod_version is not
# available. In this case, we check for the availability of module
# mod_authz_core (which should be on 2.4 or higher only) as a best guess.
<IfModule mod_version.c>
	<IfVersion < 2.4>
		<Files "config.php">
			Order Allow,Deny
			Deny from All
		</Files>
		<Files "common.php">
			Order Allow,Deny
			Deny from All
		</Files>
	</IfVersion>
	<IfVersion >= 2.4>
		<Files "config.php">
			Require all denied
		</Files>
		<Files "common.php">
			Require all denied
		</Files>
	</IfVersion>
</IfModule>
<IfModule !mod_version.c>
	<IfModule !mod_authz_core.c>
		<Files "config.php">
			Order Allow,Deny
			Deny from All
		</Files>
		<Files "common.php">
			Order Allow,Deny
			Deny from All
		</Files>
	</IfModule>
	<IfModule mod_authz_core.c>
		<Files "config.php">
			Require all denied
		</Files>
		<Files "common.php">
			Require all denied
		</Files>
	</IfModule>
</IfModule>