Connection 2 FreePBX?

Question

Asterisk

Greetings,
there is 1 main PBX on FreePBX 14 to which several operators are connected and working.
We connected a local operator, but he delivers sip via his ethernet cable. By cable, they serve only their local network, in connection with this, a plug was obtained, if you screw it to the main PBX, then other numbers are cut off.
Therefore, we raised a second PBX with the same Freepbx14 on which the internal number (pjsip) comes by trunk to the main PBX.
Everything seems to work, but after a month or two. Communication interruptions began, even internal ones, got into AsteriskInfo and there Active SIP Channel (s): 2454, and it can rise up to 9-12 thousand, looked in the console, all connections come from the second PBX, and these are not calls. What could be the reason?