Two Mikrotik Disconnected

Dear All,

I have a problem with RouterOS, for 2 weeks its been test with diagram below and no problem:

Internet → Cisco Switch → RouterOS (Bridge) → 1 Server

But when i migrate to:

Internet → Cisco Switch → RouterOS (Bridge) → CCR1016 (Bridge) → Cisco Switch → 20 Server

I have problem after 7 hours and the connection from RouterOS to CCR1016 are been disconnected, i have no idea what the cause of disconnected, i dont think its because of firewall rules because i didnt see any of my network IP are blocked on RouterOS, may i know what the cause of disconnected ?

Please help. TQ