[RT-AC68W] Slow wifi using VPN client, but not using wired

I have an RT-AC68W with the 384.4 firmware, and a VPN client enabled and setup to PIA. My Internet connection speeds are 60Mb (down)/5Mb (up) .

Using a wired connection (laptop) without going thru the VPN I get 63/5, and using the VPN I get 60/5 (no problem here). When I go wireless (laptop) without the VPN I get 60/5 (no problem) and using the VPN I get 25/5 (problem here). I've tried this on a second laptop and a tablet (only wifi with this of course), and the results are always the...

[RT-AC68W] Slow wifi using VPN client, but not using wired