SSH connection - The remote system refused the connection - 03.03.05SE

[ciscoAvi]

I suddenly lost connection to a 3650 SW running 03.03.05SE IOS. Does anyone know if there is a common bug on this IOS who does this?

[Austin Sabio · Accepted solution]

It's not necessary a bug. Does the switch still forward packets? Is it online? Is it reachable with icmp? Mostly, if this is the case then the switch may be running low on memory resources then a reload is required best option is to console and find out what's the issue. 

I hope this helps. Please don't forget to mark correct and helpful answers. Good luck!

- Austin

[ciscoAvi]

Thanks for the response. It does still forward packets and smtp packets, and yes we can still ping it. I will try to do that. Is it a good practice to upgrade the IOS also when I can access it again?  

[Austin Sabio]

This leads to different questions when to upgrade the code and which version to go with. Typically, a good practice is to maintain same code for certain platform on all devices. You need to select a proper version of code based many factors such as cisco recommendation, thorough analysis of ios release notes and how old is the image certainly when dealing with core switches. However, sometimes certain conditions trigger software bug which requires code upgrade or downgrade. so to answer your question, is it a good practice to upgrade the code every time you run into a problem? No. collect information by checking the logs and uptime before you reload the switch. Good luck!

-Austin