Was gonna say, I explicitly recalled it being the removal of the scaling algo, so if anything the current vote counts (this has possibly changed since that 2016 adjustment) are more accurate. Reddit has a massive userbase, and posts in default subs are naturally going to get upvoted substantially. There’s no real viral algorithm to reddit, you just see things that are upvoted.
Because you’re serving the website on a non-standard port, you will always need to provide the port in the web browser.
That said, I don’t see anything wrong here. It looks like you’ve got the right ports set, TCP should be correct. You may not get a ping, because ICMP is likely not enabled at the modem. When you ping, you ping the first device that’s exposed to the internet, not an open server.
Just to be sure, when you’re on your phone, you’re using data? If you’re on wi-fi, the modem/router may not be configured to perform NAT reflection, so you won’t be able to access anything via your WAN IP.