So I recently had the need to forward port 80 to an Apache server at my house. I forwarded port 80 to the IP address of the server and everything was okay (I could hit the webpage from outside my network). Then about 10 minutes later it stopped working. I went back into my router, checked the settings (still good) and then hit save. Everything started working again.. except 20 or so minutes later it stopped working.
I actually have another Apache server so I booted it up and tried forwarding the ports to it and I get the same behavior.
If I'm within my home network and I type www.mydomain.com/website/ I can hit it fine. But if I use something that is not on my network, like my phone on LTE, and try it it will fail with "webpage cannot be found". But the same link, from within my network, works fine. So then I go into the router, simply re-save the configuration, and then it works again for like 10-30 minutes.
What could be causing this?!? It's such a weird problem to have!
In the logs when everything stops working I get this message a bunch of times "Blocked incoming TCP SynAck packet" there is some IP information associated with that error.