n2n supernode connection issue with n2n_embed while edge works

[ming202012]

I encountered a problem when using n2n_embed of n2n. The prompt is: sudo./example_edge_embed
06/Oct/2024 20:09:10 [edge_utils.c:3564] adding supernode = localhost:7777
06/Oct/2024 20:09:10 [edge_utils.c:399] number of supernodes in the list: 1
06/Oct/2024 20:09:10 [edge_utils.c:401] supernode 0 => localhost:7777
06/Oct/2024 20:09:10 [edge_utils.c:490] successfully created resolver thread
06/Oct/2024 20:09:10 [edge_utils.c:1147] successfully joined multicast group 224.0.0.68:1968
06/Oct/2024 20:09:16 [edge_utils.c:1556] WARNING: supernode not responding, now trying [localhost:7777].

However, when I use edge, I can connect to the supernode (localhost:7777). What could be the possible reason? :localhost:7777