This is an easy-to-set-up VPN to use, with a well-known privacy-oriented company, and it's fast, i.e. the speed drop is not at all noticeable even with the free (non-media) bandwidth.

Unfortunately, if the extension is kept running while the computer goes to sleep, etc., the internet connection for the browser becomes unstable, including not being able to connect to any website. Turning off the extension restores the normal connection, but turning the extension back on still causes problems. At this point, removing and reinstalling the extension is required to get it working again. This is non-ideal. Some other reputable VPN providers may be easier to work with than this.

Good extension, but I confirm the bug reported by another user. If I close Firefox (Ubuntu snap) with the VPN connected and shut down my computer, at restart when I launch Firefox there's a notifiation indicating that the VPN is connected but the browser cannot reach any website and the extensions seems broken (blank menu on icon click). The only way to retrieve a working Firefox situation is to unistall the extension (if only disabled, Firefox stops working when reenabled).

Edit: A full re-install doesn't seem required, if you go to manage extension > disable > enable then it seems to make it work again.

Sometimes bugs out and requires a full re-install to work again.
From my limited testing it seems to be related to closing the browser while the vpn is connected.

Servizio molto semplice, comodo e che rispetta la privacy

firefox and linux broken. both versions have authentication persistence issues. log out, disable, re enable, re log is only fix. been like this for ages. why does the linux version suck so bad in comparison of windows....

With only this vpn specifically proton services are not reachable, but work with different vpn.
what a joke !!!

Proton is a really good service, but VPN latence is really bad compared to NordVPN which is one that I tried also!

This add on, is constantly having problems with Firefox, works fine in other browsers like Vivaldi, it was working on Firefox, suddenly when I connect, the addon on Firefox, it begin to give me this message to all sites:
"
Secure Connection Failed

An error occurred during a connection to google.com. Cannot communicate securely with peer: no common encryption algorithm(s).

Error code: SSL_ERROR_NO_CYPHER_OVERLAP

The page you are trying to view cannot be shown because the authenticity of the received data could not be verified.
Please contact the website owners to inform them of this problem."

NOTE: I don't have the Proton VPN client working on windows, just using add on with browser.

I'm using this on linux mint, and basically whenever i install it, it will work for a few hours. Then the next day when i try to load any page, it will fail. Even if I disconnect from the VPN it still fails. The only thing that works is to delete the entire extension and redownload it and log in, which takes too long.
Need to fix this issue, otherwise app unusable

Funciona, y funciona bien.

The best vpn, thanks to this now all my ecosystem is proton. One part that it sucks is in drive you just have 2 GB and that is not enough for me. But with the VPN in my opinion IS THE BEST VPN ADDON

Works well.
Used on my phone for a while, now switched from google chrome to Firefox exclusively at home and on my phone, works perfectly between my PC and my phone.
I have also just subscribed to their premium $20 per month plan.
Well worth it! I have used their emails and drive as well for a while now. Great product suite