not specifically a vMix question - we are trying to execute Teams NDI to vMix using a 5G router (Huawei). We periodically experience choppy video and or audio from some or all of the participants (we were only on a call of 6, and only capturing 4). I'm trying to understand the technical side of what components are doing what, as enabling NDI definitely caused this issue, and turning off NDI definitely fixed it.

I imagine that the laptop is doing a lot of processing but can anyone think of a reason why this is happening. The laptop has a Killer 2.5Gbps interface, the cable is Cat 5e and the router is Huawei CPE Pro 2. We are only using one laptop to capture and stream the content.

If you do all on the same computer NDI never leaves it, so I highly believe a resource issue. As Richard said, try to split the load. One does Teams NDI out. One does vMix streaming and recording. Second, the 2.5G killer network can only be utilized if the router/switch also supports it. Check the negotiation what speed you really connect with. The Pro 2 only supports 1G. If you want to do more over the mobile network you may want to use some bonding solution.