My gluetun VPN keeps failing the health check after running for a few hours. I found that some had fixed this by changing the update period to a shorter interval, and this worked for a while for me as well. But for the last 24h or so, it keeps failing after a few hours.
Something similar kept happening to me last year, constantly disconnecting no matter what I tried. I thought it was a gluetun issue so I stopped using docker and tried the official ProtonVPN app, openvpn, wireguard and community version of protonvpn, I tried switching from arch to ubuntu on my NAS and the same thing kept happening.
I was convinced it was a hardware issue so I tried different hardware, same issues.
The only thing that fixed it was reducing the number of torrents I had seeding. At the time I had ~500 and once I lowered it, I stopped disconnecting.
Now I run 3 gluetun containers with 1 qbittorrent container connected to each and they each have ~400 torrents seeding and I haven't had any issues since.
The size of the file and speed shouldn't be an issue, unless its crazy high speeds, I'm seeding a bunch of 80+ GB files, I think for me it was the number of connections being made that was causing the disconnects for me.
I'd try a few different countries and see if its that specific one, I like to have 3 different countries listed in my compose files so if there are issues with one countries servers it just connects to the next country instead