Warpinator 1.8.3 Flatpak on cannot connect Fedora 39 and Mint 20.3 Cinnamon - display "no other computers found"

[Groberen]

Distribution

Fedora 39 Cinnamon

Package version

1.8.3 Flatpak

Frequency

Always

Bug description

Two computers that have installed same version of Warpinator:

• Linux Mint 20.3 Cinnamon. There was an older version from Mint repository that was uninstalled before installing the flatpak version. Computer name is Optiplex.
• Fedora 39 Cinnamon. Same version of Warpinator installed. Have not being any version of Warpinator on that computer before.

This is the things already checked out (and probably not the cause why Warpinator doesn't connect)

• Both computers can ping each other.
• According to a source on web (old bug?) - the settings in both Warpinator are the network interface is specified (i.e. not "automatic").
• Group name is set the same on both sides, several variants tested and always same issue.
• Same network is known to work with Warpinator - couple of weeks ago, two Mint computers using the Warpinator version from software manager was able to pass files over the network.
• No firewall is active in either of the computers.

The result is that Warpinator on both sides display
flatpak_warpinator_debug-Optiplex.txt
flatpak_warpinator_debug-Acer.txt

Steps to reproduce

First - ensure Network/firewall isn't a issue.

Linux Mint 20.3 Cinnamon

• Install Warpinator from software manager, then uninstall (don't know if this is relevant)
• Install flatpak version "$ flatpak install flathub org.x.Warpinator"

Fedora 39 Cinnamon

• Install flatpak version "$ flatpak install flathub org.x.Warpinator"
• Run Warpinator - set up group name and specify network interface (latter step doesn't matter).

Linux Mint 20.3 Cinnamon

• Run Warpinator - set up group name, same as the Fedora computer.

Expected behavior

Warpinator on both sides is expected to find each other.

Additional information

Before I installed the flatpak version of Warpinator on the Optiplex computer, there was the version default to Linux Mint installed (1.4.5 if I recall correctly).
At this point, the Acer computer had the newer flatpak version (1.8.3) and I didn't realize there was different software version.

However, the GUI behavior on the Acer side was different then, compared to when both computers had 1.8.3 flatpak version.

When the Optiplex computer had 1.4.5 version, on the Acer I could observe that it was able to see, i.e. the name and IP of the Optiplex was appearing, but also with text toggling between "attempting to connect" and "unable to connect".
Unfortunately I didn't take screen shot or log file from this because I wrongfully taught that when both computers used same version of Warpinator, should fix the issue.