Error applying iptable rules

[git2fa]

Describe the bug
AFWall+ V4.1.0 is installed on an Samsung Tablet running CyanogenMod 13.1 with Android 6.0.1
The APP could be installed and seems to work normal.
But when you try to enable the firewall there is only an Popup "Error applying iptable rules" and the firewall keeps deactivated.

Before this popup is shown there is a popup with "Applying Rules for V4" and "Applying Rules for V6".
It is so short that you need to film it with a camera to read it as stand picture.

In the Original Android 4.4 AFWall+ was working before.

IP-Tables

iptables seems to work normal, because in the console there is a result for "iptables -L".

iptables.txt

Magisk is installed and AFWall+ has full root privileges.

Firewall Logs
The log can be enabled but there is never any content shown in the log.

Smartphone (please complete the following information):

• Device: Samsung Tab3 GT-P5200
• Android OS: 6.0.1

[git2fa]

Maybe found a reason for the problem in the output of "Show rules":

error.txt

Here you can find:

13:26:33 Refreshing FirewallService notification
13:26:33 command '/system/bin/iptables -n -v -L -w 5' exited with status 2

The command "iptables -n -v -L -w' works only without the 5.
With 5 the result is Bad argument '5'
So it seems that iptables is being called with illegal parameters.
The kernel is version 3.4.34

The iptables manual for kernel 5.10 says

       -w, --wait [seconds]
              Wait for the xtables lock.  To prevent multiple instances of the program from running concurrently,  an  attempt  will  be
              made  to  obtain an exclusive lock at launch.  By default, the program will exit if the lock cannot be obtained.  This op‐
              tion will make the program wait (indefinitely or for optional seconds) until the exclusive lock can be obtained.

and iptables --help shows the same for -w on the tablet.
So it is not understandable what is going wrong here - the command iptables seems to be broken.
No idea how to fix it?

[git2fa]

Extracted today the iptables from the backup of the Android 4.4 and placed it in /data/data/dev.ukanth.ufirewall and made it executable.
The command can be executed and gives back the version 1.4.11.1 (Android 6.0.1 is version 1.4.20).
More interesting is that this older command does not support the --wait option at all!
The command "iptables -n -v -L" gives back an correct result.

So how to get rid of the Bad argument '5' ?