Here’s the lab.
I got a problem running EIGRP after several changes. It seems that no router would establish neighborships anymore.
The “debug eigrp packet hello” on HQ router showed that it does not receive hellos out its serial interface.However, the configuration is correct.
I configured EIGRP once again; and it solved the problem.
Now, did I miss something? I did not find it. That does not matter, everything runs smooth once again:)