Hello Jose.
As Rob PE1CHL wisely pointed just while ago...
Run command:
ampr-ripd -d -r -i <44-tunnel-interface>
You should see something similar:
root@linux:/# ampr-ripd -d -r -i tunl0
Waiting for RIPv2 broadcasts...
Simple password: dumbpassword
...
Simple password: dumbpassword
Running above command from the command line on my server
Debian-7.9 i686 machine WITHOUT "-r" also does not work!!!
So, it seems that it is NOT only Pi specific...
Alternatively, you may set up manually single route to ANY working
44-net host to see whether you will be able to reach that gateway.
Best regards.
Tom - SP2L