Call the configuration page of your FritzBox in a browser of your choice with the URL: fritz.box and log in afterwards.
To activate port forwarding for a FritzBox, use the left-hand selection menu to navigate to “Internet” and then “Sharing”. Click on the field “Add device for shares”.
Then select your device from the drop-down menu. Next, you must click the “Allow independent port sharing for this device” checkbox.
After the device has been added, you must release the ports 80 and 443. To do this, click on “New Release” at the bottom right.
Important: Please do this step for both Ports!
Once you have added both ports, click OK. Finally, you only need to enable the independent port sharing.
To check the release, go to Diagnostics for Security and check the released ports in the item Connection, Internet.
How to activate port forwarding with a TP-Link router can be found here: https://www.noip.com/support/knowledgebase/setting-port-forwarding-tp-link-router/
How to enable port forwarding with a Netgear router can be found here: https://kb.netgear.com/en/24290/How-do-I-add-a-custom-port-forwarding-service-on-my-Nighthawk-router
How to enable port forwarding with a Netgear router can be found here: https://support.google.com/wifi/answer/6274503?hl=en