Forbidden - You don't have permission to access / on this server.

WAF Logs (editted the domain name part)

Setting up WAF takes some effort.  It looks like you've just drastically modified the "Basic Protection" Profile instead of starting it in "Monitor" mode and making sure you can connect first.  The log is confusing me because you don't have 'Static URL hardening' selected.

Cheers - Bob

Thanks. 

I have set the Basic profile as follows:

And retaken a capture of the logs here:

2018:07:09-01:05:34 ids httpd[416]: [url_hardening:error] [pid 416:tid 4063746928] [client 125.236.212.159:19506] No signature found, URI: http://files.xxxxx.co.uk/
2018:07:09-01:05:34 ids httpd[416]: [url_hardening:error] [pid 416:tid 4055354224] [client 172.18.175.138:33718] Hostname in HTTP request (172.18.175.138) does not match the server name (files.xxxxx.co.uk)
2018:07:09-01:05:34 ids httpd: id="0299" srcip="172.18.175.138" localip="172.18.175.138" size="209" user="-" host="172.18.175.138" method="GET" statuscode="403" reason="-" extra="-" exceptions="-" time="412" url="/" server="files.xxxxx.co.uk" port="80" query="" referer="-" cookie="-" set-cookie="-" uid="W0K03qwSr4oAAAGgAeIAAAA7"
2018:07:09-01:05:34 ids httpd: id="0299" srcip="125.236.212.159" localip="172.18.175.138" size="177" user="-" host="125.236.212.159" method="GET" statuscode="403" reason="-" extra="-" exceptions="-" time="2850" url="/" server="files.xxxxx.co.uk" port="80" query="" referer="-" cookie="-" set-cookie="-" uid="W0K03qwSr4oAAAGgAeEAAAA6"
2018:07:09-01:05:35 ids httpd[416]: [url_hardening:error] [pid 416:tid 4046961520] [client 125.236.212.159:19510] No signature found, URI: files.xxxxx.co.uk/favicon.ico
2018:07:09-01:05:35 ids httpd[416]: [url_hardening:error] [pid 416:tid 4038568816] [client 172.18.175.138:33719] Hostname in HTTP request (172.18.175.138) does not match the server name (files.xxxxx.co.uk)
2018:07:09-01:05:35 ids httpd: id="0299" srcip="172.18.175.138" localip="172.18.175.138" size="220" user="-" host="172.18.175.138" method="GET" statuscode="403" reason="-" extra="-" exceptions="-" time="419" url="/favicon.ico" server="files.xxxxx.co.uk" port="80" query="" referer="-" cookie="-" set-cookie="-" uid="W0K036wSr4oAAAGgAeQAAAA9"
2018:07:09-01:05:35 ids httpd: id="0299" srcip="125.236.212.159" localip="172.18.175.138" size="185" user="-" host="125.236.212.159" method="GET" statuscode="403" reason="-" extra="-" exceptions="-" time="2247" url="/favicon.ico" server="files.xxxxx.co.uk" port="80" query="" referer="-" cookie="-" set-cookie="-" uid="W0K036wSr4oAAAGgAeMAAAA8

Thanks. 

I have set the Basic profile as follows:

And retaken a capture of the logs here:

2018:07:09-01:05:34 ids httpd[416]: [url_hardening:error] [pid 416:tid 4063746928] [client 125.236.212.159:19506] No signature found, URI: http://files.xxxxx.co.uk/
2018:07:09-01:05:34 ids httpd[416]: [url_hardening:error] [pid 416:tid 4055354224] [client 172.18.175.138:33718] Hostname in HTTP request (172.18.175.138) does not match the server name (files.xxxxx.co.uk)
2018:07:09-01:05:34 ids httpd: id="0299" srcip="172.18.175.138" localip="172.18.175.138" size="209" user="-" host="172.18.175.138" method="GET" statuscode="403" reason="-" extra="-" exceptions="-" time="412" url="/" server="files.xxxxx.co.uk" port="80" query="" referer="-" cookie="-" set-cookie="-" uid="W0K03qwSr4oAAAGgAeIAAAA7"
2018:07:09-01:05:34 ids httpd: id="0299" srcip="125.236.212.159" localip="172.18.175.138" size="177" user="-" host="125.236.212.159" method="GET" statuscode="403" reason="-" extra="-" exceptions="-" time="2850" url="/" server="files.xxxxx.co.uk" port="80" query="" referer="-" cookie="-" set-cookie="-" uid="W0K03qwSr4oAAAGgAeEAAAA6"
2018:07:09-01:05:35 ids httpd[416]: [url_hardening:error] [pid 416:tid 4046961520] [client 125.236.212.159:19510] No signature found, URI: files.xxxxx.co.uk/favicon.ico
2018:07:09-01:05:35 ids httpd[416]: [url_hardening:error] [pid 416:tid 4038568816] [client 172.18.175.138:33719] Hostname in HTTP request (172.18.175.138) does not match the server name (files.xxxxx.co.uk)
2018:07:09-01:05:35 ids httpd: id="0299" srcip="172.18.175.138" localip="172.18.175.138" size="220" user="-" host="172.18.175.138" method="GET" statuscode="403" reason="-" extra="-" exceptions="-" time="419" url="/favicon.ico" server="files.xxxxx.co.uk" port="80" query="" referer="-" cookie="-" set-cookie="-" uid="W0K036wSr4oAAAGgAeQAAAA9"
2018:07:09-01:05:35 ids httpd: id="0299" srcip="125.236.212.159" localip="172.18.175.138" size="185" user="-" host="125.236.212.159" method="GET" statuscode="403" reason="-" extra="-" exceptions="-" time="2247" url="/favicon.ico" server="files.xxxxx.co.uk" port="80" query="" referer="-" cookie="-" set-cookie="-" uid="W0K036wSr4oAAAGgAeMAAAA8

This is screen I get when I browse to the URL:

I suspect that you have no such problem if 'Static URL hardening' is not selected.  If so, then since you've already tried enabling/disabling URL rewrite and pass host headers, this would indicate that your website is returning URLs that contain fixed IPs - can you check that?

Cheers - Bob

Ok thanks alot for the reply

Any idea how I can check if my web server is returning an IP address? 

I'm fairly certain that it is and that the programmer for your site will know how to fix it or that it's too complicated to fix at a reasonable price.

Cheers - Bob