Getting Remmina's Proxy into Its Flatpak Sandbox

An export in a terminal can be perfectly valid and absent from the Remmina process you launched from the desktop. For a Flatpak installation, check the application's own environment overrides.

Flatpak provides a per-user, per-application configuration surface. An example for an HTTP proxy endpoint is:

flatpak override --user --env=https_proxy=http://proxy.example:8080 org.remmina.Remmina

Use the installed application's actual ID and the endpoint's supported protocol. The variable name describes the setting consumed by the networking library; it does not require the value to start with https://.

FreeRDP's proxy implementation reads https_proxy and HTTPS_PROXY when an explicit proxy type has not already been selected. A Remmina build and connection type must actually use that path. An SSH, VNC, and RDP profile are not three interchangeable consumers.

Completely close the existing application before starting it with the new override. Saving an override does not rewrite a process already running inside the sandbox.

To remove this particular override, Flatpak also supports:

flatpak override --user --unset-env=https_proxy org.remmina.Remmina

Keep credentials out of shared command output. An application override is configuration, not a password vault. If TCP reaches the proxy but the desktop connection still fails, retain the selected profile, transport, and proxy response; changing more host-shell exports cannot repair a protocol or authorization failure inside that connection.