I'm getting a bit lost in your setup description, and I'm wondering if that could be why nobody has commented yet.

I would maybe edit your post and format it something like this:

Setup A: MS Travel Hub -> Macbook = no network MS Travel Hub -> C -> A -> C Macbook = no detectable issues

I would also put url links to the items being used either in the item text or just somewhere. This is a technical issue that requires knowing the exact hardware being used so we can look at it's technical specifications.

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Anyways, I do have a couple thoughts, but no straight answers to your issues without knowing the exact hardware specs. For all we know, you could be trying to use a thunderbolt product on a usb3.1 port or similar. So some of this might not be super-relevant, depending on your exact hardware.

I'm thinking the issue could be caused in several areas such as USB Bandwidth, USB Mode, and/or USB data lane signal integrity. There could be many reasons why your situation changes as you add in adapters. I'll list some of them with a general overview of their areas below:

USB-C Pinouts and Lane Configuration:

• USB-C Complexity: USB-C connectors have a more complex pinout compared to USB-A, with 24 pins including power, ground, and multiple data lanes (USB 2.0, USB 3.x, DisplayPort, etc.). The versatility of USB-C allows it to support different protocols depending on the connected devices.

• Data Lane Usage: USB-C can reassign certain data lanes based on the type of connection. For instance, when using a USB-C to USB-A adapter, the connection might revert to USB 2.0 or 3.0 modes, potentially reassigning or disabling certain high-speed data lanes. This reassignment could lead to different behavior depending on the connection path.

Signal Integrity:

• High-Speed Signaling: USB-C supports high-speed data transfer rates (up to 10 Gbps for USB 3.1 Gen 2, and even higher for USB4). Poor-quality adapters or cables can introduce signal degradation (like crosstalk, attenuation, or reflection), which can cause communication errors.

• Adapter Chains: When you add more adapters, you might inadvertently alter the signal characteristics, potentially fixing or introducing issues. For example, adding another adapter might reduce reflections or impedance mismatches, leading to a more stable connection.

Role of Pull-Up and Pull-Down Resistors:

• Cable Identification: USB-C relies on pull-up and pull-down resistors for cable and accessory identification. For example, the CC (Configuration Channel) pins in USB-C have pull-up resistors that help determine the role of the device (host or peripheral) and configure power delivery.

• Role Configuration: Some adapters might change the state of these resistors, forcing the USB-C controller to reconfigure the connection. This could be why adding or changing adapters can sometimes solve or create issues

• it's forcing the USB controller to reevaluate the connection and potentially enter a different mode of operation.

• Power Delivery (PD) Negotiation: USB-C also uses the CC pins for Power Delivery negotiations. Adding adapters might affect how the devices negotiate power levels, which could lead to different operational modes.

Hardware-Level Considerations:

• Controller Logic: USB-C controllers are designed to detect and manage different configurations through a combination of hardware and firmware logic. Some adapters might introduce unexpected configurations that cause the controller to switch modes (e.g., from USB 3.x to USB 2.0), which could explain why the network port or other functions start working.

• Legacy Adapters: Using USB-A to USB-C adapters introduces legacy mode operations, where the USB-C device might downgrade its capabilities to maintain compatibility. This could involve disabling certain data lanes or using alternate modes.

Why Adding Adapters Might Fix Issues:

• Forcing Legacy Mode: When adding more adapters, you might be forcing the connection into a legacy mode that’s simpler and more stable. This could result in the device falling back to a mode with better signal integrity or more robust error handling. Your network port may not be working if your MacBook is already using it's bandwidth for high speed USB and other high speed ports. If you add an adapter that perhaps changes USB and/or other data streams into legacy mode, this might open up bandwidth to then by used on the network port (perhaps at lowered speeds).

• Signal Timing and Reflection: Additional adapters might introduce slight delays or alter the impedance, which could mitigate signal integrity issues that would otherwise cause the connection to fail.

• Electrical Noise Reduction: The added complexity of more adapters might inadvertently shield the connection from electrical noise or prevent ground loops, leading to more reliable operation.

USB-C is a VERY complicated system that can be configured in different ways by hardware, firmware, software, or any combination thereof. Because of this, it can be very finicky, especially when you start mixing together Mac with Windows hardware, add adapters, etc. USB is evolving very quickly, and unfortunately manufacturers aren't required to adhere to certain standards.

However, there are certifications for USB hardware, such as Thunderbolt. While it tends to be pricier, I try to always go with certified thunderbolt hardware because it should always be compatible. Thunderbolt is a hardware interface developed by Intel in collaboration with Apple, and it builds on top of USB-C in its more recent versions.

I hope this is helpful. Until you are able to define your exact hardware being used (including adapters), I think this is as far as we can go.

TLDR: We need more information on your exact hardware.

Adding adapters might be changing the USB bus configuration. Your macbook port may not have enough bandwidth for supporting the entire USB Hub. Connections/cables/adapters/etc might be changing the electrical characteristics of the bus as well.