Remote stopped working

I have Plex installed on my NAS, Synology OS. It works fine in my home on my network. I used to be able to access it remotely, but lately it stopped working, and I don’t know how to fix it. I have a static IP on my router, and I believe I set it up for the default public port on my router and in Plex. My router is a fiber unit supplied by PLDT (a Philippine Internet provider), model HG8145V5. I have tried reading the forums for suggestions and solutions, but some of the terms are beyond my understanding. I have enjoyed Plex and want to keep using it, but If I can’t access my server while I travel, I will have to change it. I have a lifetime Plex Pass; I believe my version is 1.43.5.11079

What does this say for the port you opened on your router and set in plex? https://canyouseeme.org/

Do you know if your ISP moved you behind CGNAT which would block you from being able to port forward? If you check your router, look for WAN IP. Does it fall between 100.64.0.0 - 100.127.255.255? If it’s not in that range, does it match the ip you saw at the canyouseeme link above? It needs to.

Is the static ip you mention one you paid your isp for, or just what you set on your own router for the plex server?