Connection Managers not forwarding connections

Hi, We had an upgrade for the whole informix cluster and after bringing up all the servers , couldn't resync HDR with primary because it was always causing checkpoint blocked on the primary. Afterwards, I noticed that the connection managers aren't forwarding traffic, restarted them multiple times, upgraded csdk to the last version 12.10 FC12, but nothing changed. Connection manager log says it connected successfully to primary server and on primary server onstat -g cmsm says that connection manager is connected, also reporting in online.log. I am able to connect directly to the database but i'm not able to connect to the database through connection manager. On tcpdump, there is traffic between connection manager and primary and on connection manager we can see the traffic from the clients, but nothing reaches the database also there are no writes in the connection manager log It is possible that the connection manager is not sending traffic because HDR is not paired with primary and can't connect to it ? informix db version in 12.10 FC9 and CM version is 12.10 FC12

There was an OS/bios upgrade not informix

Correction, DB version is 12.10FC11