最近用 NUC9 和 macbook air m1 搭建雷电网桥成功后，查阅 AMD 6000 系的 USB4 相关资料，发现其理论上兼容雷电 3 ，遂购入一台 SER6 MAX （ 6900HX ），尝试构建雷电网桥，但换了几个系统，都还是不成功，问题如下：
问题表现
自带的 win11 系统
可以载网络适配器中看到 20Gbps 的网络连接 (USB4 P2P Network Adapter)，mac 端 thunderbolt bridge 唤起为黄色，但手动设置 ip 后，依然无法 ping 通，提示 Host is down
网卡信息：
Link speed (Receive/Transmit): 20/20 (Gbps)
Link-local IPv6 address: fe80::9e00:9689:7fd9:c95d%39
IPv6 DNS servers: fec0:0:0:ffff::1%1 (Unencrypted)
fec0:0:0:ffff::2%1 (Unencrypted)
fec0:0:0:ffff::3%1 (Unencrypted)
IPv4 address: 10.10.10.3
Manufacturer: Microsoft Corporation
Description: USB4(TM) P2P Network Adapter #3
Driver version: 10.0.22621.2506
Physical address (MAC): 2C-1D-26-46-40-27
mac 发起 ping 的结果
(base) chengjy@chengjys-Air ~ % ping 10.10.10.3
PING 10.10.10.3 (10.10.10.3): 56 data bytes
Request timeout for icmp_seq 0
Request timeout for icmp_seq 1
Request timeout for icmp_seq 2
Request timeout for icmp_seq 3
ping: sendto: No route to host
Request timeout for icmp_seq 4
ping: sendto: Host is down
ubuntu
可自动识别到 thunderbolt bridge 并自动配置 ip ，同样无法 ping 通
truenas/unraid
操作 shell 可读取到雷电设备相关信息，但无法看到控制器具体型号 (在 NUC9 中可以读取到 JHL7540)，无法在 network 相关页显示配置，无法配置 ip 并测试 ping 通
root@Tower:~# lspci -nnk | grep Thunderbolt
00:03.1 PCI bridge [0604]: Advanced Micro Devices, Inc. [AMD] Family 19h USB4/Thunderbolt PCIe tunnel [1022:14cd]
00:04.1 PCI bridge [0604]: Advanced Micro Devices, Inc. [AMD] Family 19h USB4/Thunderbolt PCIe tunnel [1022:14cd]
e6:00.5 USB controller [0c03]: Advanced Micro Devices, Inc. [AMD] Rembrandt USB4/Thunderbolt NHI controller #1 [1022:162e]
Subsystem: Advanced Micro Devices, Inc. [AMD] Rembrandt USB4/Thunderbolt NHI controller #1 [1022:162e]
e6:00.6 USB controller [0c03]: Advanced Micro Devices, Inc. [AMD] Rembrandt USB4/Thunderbolt NHI controller #2 [1022:162f]
Subsystem: Advanced Micro Devices, Inc. [AMD] Rembrandt USB4/Thunderbolt NHI controller #2 [1022:162f]
win10 LTSC21
直接无法在网络适配器和设备管理器中找到相关设备
其中，ubuntu/truenas 系统移植到 nuc9 后，都很顺利的和 mac 构建了雷电网桥
问题资料查阅
在查阅资料时发现，USB4 并没有声明对雷电网桥的强制支持，很可能会因为系统/驱动相关的问题而无法连接。
同时在 reddit 上查到这样一段说明：
It is possible for a USB4 host to be unable to make a connection to TB1-TB3.
At the same time, it is also possible the two cannot connect. In the case of a USB4 host that can work with TB3 or earlier, it would establish on each end using their respective names. USB4NET on the USB4, and Thunderbolt Networking on the other.
The contingency in question, the very crux of what you are asking about, depends on if a USB for vendor has requested clearance to enable Thunderbolt Legacy mode.
Only Intel can provide a Legacy Thunderbolt vendor key, because they maintain the key store for pre-TB4 vendor codes.
Contrary to popular belief, Intel is not being a jerk about this. I have personally been given access by Intel to the necessary licensing paperwork.
It’s a very simple form, and they have made clear to me, that AMD, ARM vendors, and anyone else that wants to enable legacy Thunderbolt compatibility, can and will be permitted to do so.
The compatibility requires a USB vendor to install a Thunderbolt 3 VID key into their chipset firmware. This must be issued by Intel, but does not require Thunderbolt certification or licensing.
一言以蔽之，USB4 与 TB3 的点对点传输是不同的协议，需要通过 Thunderbolt Legacy mode 协议进行互信（虽然协议是免费的，但依然需要厂商挂载到 USB4 中
可能结论
所以说，需要一台可以同时满足自身通过作为 win/linux 服务器配置为 NAS+ 连接 mac 时通过雷电网桥成为类 DAS 设备的小主机，可选的只有声明带有雷电 3/4 的 NUC 设备如 1240p 的华尔街峡谷了吗？
6800H/7840H 的 nuc/笔记本茫茫多，不可能一个个都尝试过去，况且这个功能几乎不做为卖点宣传，在产品官网/售前咨询时，也是很难找到有效的信息。
参考资料
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