Sponge not accepting external Bungeecord

I have Bungeecord and Sponge on two different servers, if I try to connect from a local Bungeecord (on the same server) it connects without problems, but if I try to connect to an external Bungeecord (on different server) it does not connect.

And does it work without Sponge?

And if it still doesn’t work without sponge, it sounds like it might be a firewall issuem

it works with other servers that are not forge and without Sponge does not work

I assume there’s a kick message; could you post a picture of it?

Sometimes I have “Disconnected” and sometimes “io.netty.channel.unix.filedescriptor:-1”

Quick question: Is IP forwarding enabled on BungeeCord? If so, you’ll need to turn on IP forwarding support for Sponge by setting bungeecord to true in the Sponge config/sponge/global.conf file. If not, you’ll need to set it to false.

Yes, is enabled