cannot get to website on my server internally after isp change

I have a synology nas ds411+ which i can access internally via its login page. I have a website that I made in joomla hosted on the ds411+.

the site is which i am told is working externally and i can get to the joomla login page via a mobile network so i think all that external infrastructure works ok.

Before my isp change i could access the webpage internally by putting the website address in the chrome browser.

now it just takes me to the router log in page.

how do i access the site internally now?

regards in advance
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Zephyr ICTCloud ArchitectCommented:
is the webpage (management) of your Synology not on port 5000? E.g: <ip-of-your-synology:5000>

If it's not, maybe you can change it, so that it doesn't use the standard port 80 (if it is using it of course), you can normally change this under DSM Control Panel => Connectivity > Network > DSM Settings (I'm doing this out of my head, so I could be wrong) ...
PeterBaileyUkAuthor Commented:
yes i have access to that internally which i reach :
The website is being forwarded to, can it be that you need to login to to change the dynamic dns settings to reflect the isp change? Allthough that would imply external issues.

Do you see the website if you browse to or the internal ip equivalent of the website on the synology?
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PeterBaileyUkAuthor Commented:
thats all working correct the no-ip client runs at startup and has the correct ip address the .com and domains are forwarded correctly. its only internally now i cannot get to the sites which i need to, to update the sites etc.
Also did you change your internal IP range with the ISP change over? Do you maybe have defined in your local hosts file pointing it to the ip address that is now the router IP?

DNS aside, are you able to access the websites on their internal IP addresses?
PeterBaileyUkAuthor Commented:
previously to changing isp i could put in the url and i could get to the joomla administrator log in. now internally it only takes me to the router login page but if i use the url on my mobile network i can get to the login screen of joomla
Hi Peter,

If you access the website on your mobile network it does an outside-in connection; that works as intended as you said.

However if you access the website on your local network it uses the local (internal) IP address of the website (unless it's forced to somehow use the external website which leads to a hairpinning situation). This is why I was asking if you are able to correctly connect to the website if you directly connect to http://internalip. If you are able to pinpoint if you are able to access the website(s) on their internal IPs it will tell us that the issue is DNS related, if there is only one internal IP address (the router IP) then we need to check that the router isnt using port 80 on the internal side of the network and is thus blocking access to the webserver.

Basically trying to first make sure the websites are accessible on their internal IPs, then trying to figure out what changed and what was providing the FQDN service (i.e. local dns server, hosts file, router).

Ps. hairpinning is where you are trying to access an internal ip address from an internal ip address whilst going through the firewall (inside->outside->inside).
PeterBaileyUkAuthor Commented:
I am not sure what the syntax is to access the site internally i know the ip of the server is fixed @ I know that currently the site is using port 80 on its virtual server of course that's from outside.
Ah ok, no problem, you can always access a website through an ip address directly by using the following syntax in your browser:

[protocol][ipaddress][optional port number]

So in your case that would be:
(full syntax for completeness sake of the example

Does that display the website or the router page?
PeterBaileyUkAuthor Commented:
i have read that the router does not have nat loopback. could this be a part of the problem?
PeterBaileyUkAuthor Commented:
no takes me to the router login as usual.
Zephyr ICTCloud ArchitectCommented:
I know that normally when you browse to the ip-address of the Synology a redirect will bring you to the 5000-port address, this is a setting in Apache, it's supposedly also triggered when there's an issue with the website (when configured) on port 80.

So, the question would be, if the statement above is correct, what changed that would make Apache redirect to 5000 ... It supposedly looks for a "sample.php" file or something ... I'd need to read up on it again though ... Maybe it can help pinpoint the issue?

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PeterBaileyUkAuthor Commented:
my knowledge is not a lot on these infrastructure issues, I know that in the webservices section of the synology all website folders resolve to their no-ip equivalents on port 80 as attached.

The only change has been the router which is a zte h218n
PeterBaileyUkAuthor Commented:
ok got it.
PeterBaileyUkAuthor Commented:
thank you
Just turn off external management on the router.  It's intercepting your packets going to port 80, and presenting the router's own login screen, rather than allowing them through to the NAS.
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