With a 3640 I think that it is less likely to be a hardware issue and more likely a software issue, though it would be nice to know which Ethernet card it was to be sure.
I believe that it is more likely an issue of which feature set your client is running than to be an issue of which version. If you post the output of show version we would be in better position to know which version and feature set and possibly to give you a better answer.
Thanks for posting additional information. But what we need to determine the feature set is not included in what you posted. In particular we are probably looking for the line in show version that says system image is ... Or posting the output of show flash would probably give us the complete image name.
Now I believe that we have what we need. The image that you are running is the IP ONLY feature set and does not have support for dot1Q VLAN trunking. If you upgrade the feature set to the IP PLUS feature set (or more capacities) then VLAN trunking is supported.
You could keep the router at the same release level or you could take it as an opportunity to go to a more recent version of code (which would probably include more fixes for vulnerabilities). But the essential thing is to go from the IP ONLY feature set to something with more capabilities.
We are pleased to announce availability of Beta software for 16.6.3.
16.6.3 will be the second rebuild on the 16.6 release train targeted
towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are
looking for early feedback from customers befor...
Introduction Featured Speakers Luis Espejel is the Telecommunications
Manager of IENova, an Oil & Gas company. Currently he works with Cisco
IOS® and Cisco IOS XE platforms, and NX to some extent. He has also
worked as a Senior Engineer with the Routing P...
In this session you can learn more about Layer 3 multicast and the best
practices to identify possible threats and take security measures. It
provides an overview of basic multicast, the best security practices for
use of this technology, and recommendati...