Yeah, a solid yellow light on a child node means it has a weak connection to the parent node. That'll definitely slow things down.
The fix is to improve the node placement. Move the child node closer to the parent node. Reduce obstacles like thick walls or large metal objects between them. The goal is to get that light to turn solid blue.
If you're only using one node and the light is yellow, that's not a defined status. Check that the node is properly connected to your modem via the yellow Internet port with an Ethernet cable. Run a Speed Check in the app to see your actual download/upload rates—performance depends on your ISP plan, local traffic, and how many devices are online.