VPN Not Masking IP while tethered

I am tethered to an ASUS AC68U router flashed to merlin 380.66_4. I have followed guides to setup PIA as an open vpn client on the router. It says its connected and shows traffic. I also can navigate the web fine (minus sometimes getting long 'resolving host' periods while loading especially google searches). However, it isn't really working, because PIA's own whatsmyip shows it still loaded as Tmobile (see pic above).
If I start the desktop PIA and leave the VPN running on the router it will mask the IP address (see picture below). However, it makes the internet randomly not load pages, and speedtest shows the DL speed being the same, but UL speed is zero or hangs indefinitely - so not really a functional connection.

Anyone understand why PIA isn't working properly under this scenario?
Comments
Your router isn't working properly, which would suggest a fault in your set-up. I would suggest searching online for another guide and comparing it to what you already did,
https://helpdesk.privateinternetaccess.com/hc/en-us/articles/227852327-Setting-up-an-Asus-Router-running-Merlin-Firmware
Here are my settings (I ommitted my username in the picture):
I tweaked a few settings based on this post:
https://www.privateinternetaccess.com/forum/discussion/comment/38064/#Comment_38064
The only things that were changed were - I changed legacy/fallback cipher from AES-128-CBC to Default, I had tls-client added in the custom configuration setting, and I had port 1194 (which wouldn't connect at all, so I changed it right back to 1198). I think the tls-client was giving trouble too, so I removed it.
However, under either state, even if the system showed itself as connected, the traffic was not being masked as the IP address still showed T mobile.
Anyone have any other suggestions?
Cheers.