My first impression from the adhesion issue (which doesn’t appear to be the main issue of this post) is that you may need to clean your build plate. But considering it was relatively good as it is, I assume you did and the few spots may just be accidental touches to the surface. In either case, their guide is here: https://wiki.bambulab.com/en/filament-acc/acc/pei-plate-clean-guide

As for the extrusion issue - considering the apparent randomness of it my guess would be either an issue with the filament or a partial clog.

Yup, with PIA the port is random but yes, there should be scripts out there to leverage PIAs forwarding with your torrent software. And yeah, if you were to port forward through your router that could lead to accidentally exposing your actual IP.

incompatible with port forwarding with any VPN

I’m not sure if there is a misunderstanding here, but port forwarding through a VPN is generally agnostic of most network setups. It’s a tunnel, doesn’t require your network to have port forwarding setup or even for it to be capable of it.

A VPN introduces a new party who can harvest your data. It doesn’t avoid IP tracking, it just shifts it from your ISP to another entity.

You have to trust that your VPN provider’s claims of no logging/tracking are accurate, you can usually get fairly confident with research but it’s never 100%.

Edit: to clarify, I’m not trying to dissuade VPN use. It’s a still a great choice.