Wierd network issue

Good "yourpartoftheday",

​

I am running into some wierd issue and I wish to ask you guys for some advice on where to look.

We are having connection issue with a door controler (Kantech KT-400) that we are using. At some point during the night, the controler lose it's connection to the server.

​

After some troubleshoot here is how we resolve the issue :

Step 1 - Unplug the device from the switch

Step 2 - Connect a Laptop on the same port as the controler and ping the server (The reply is good)

Step 3 - Plug the controler back and NOW evertying is back online

​

Here are more information :

- The controler when it lose it's connection to the server is pingable from the server

- We tried to change the port from the switch and it doesnt change anything

- We tried to replace the controler with a new one we still have the issue

- A simple "shut/noshut" on the interface doesnt resolve the issue

- I can ping the server and the controler from the switch and both reply correctly

- It only happen on a specific subnet, all the other subnets are ok

- The trafic flow goes through an ASA but the rules are correctly setup and there are no NAT.

​

Let me know if there are some information missing.

Thanks !

​