NAT Loopback

Some routers do not support accessing devices in local network by their external router IP address (NAT Loopback). More details here: https://en.m.wikipedia.org/wiki/Hairpinning

Workarounds:

1. DNS Server

Install Pi-Hole app on Syncloud device and make it your primary DNS Server on your router.

Then under Pi-Hole -> Local DNS -> DNS Records add an override per app you use, for example:

nextcloud.me.syncloud.it -> 192.168.1.101

Where me.syncloud.it is your domain name and 192.168.1.101 is your local network IP address of your device.

2. New router

You may need to buy a better router with this feature.

You may check your router here: http://opensimulator.org/wiki/NAT_Loopback_Routers

Or by googling: [your router name and model] nat loopback

Sometimes you may want to put your new router with NAT Loopback feature in front of your provider's router when you cannot just replace it. In this case you need to put provider's router into a bridge mode first and then your internal router will be able to get a public IP.

https://kb.netgear.com/000028987/When-to-put-modem-into-bridge-mode

3. Hosts file

You may workaround this problem by adding hosts records on each PC:

https://github.com/syncloud/platform/wiki/Custom-domain#hosts-file-only-if-you-have-no-dns-server

Some routers do not support accessing internal LAN devices by its public router IP address and a port mapping from inside the local network.