tailscale 自建 derp stun IPV6 no, but OS has support 不工作

Access controls：

{
	"randomizeClientPort": true,
	"derpMap": { 
		"OmitDefaultRegions":true,
		"Regions": {
		"900": {
			"RegionID": 900,
			"RegionCode": "GZ",
			"RegionName": "tencent",
			"Nodes": [{
			"Name":             "a",
			"RegionID":         900,
			"HostName":         "ts-derp.xxx.com",
			"DERPPort":         443,
		}]},
	}},
	"nodeAttrs": [
		{
			"target": ["*"],
			"ipPool": ["100.64.18.0/24"],
		},
	],
}

1 、使用自建 DERP ，OmitDefaultRegions:True 屏蔽官方节点开启结果：IPV4 stun 正常，ipv6 no, but OS has support

tailscale netcheck --verbose
2025/09/02 12:34:49 netcheck: sent to x.x.x.x:3478
2025/09/02 12:34:49 netcheck: sent to [2402:4e00:xxxx:xxxx:xxxxxx]:3478
2025/09/02 12:34:49 portmap: [v1] Got PMP response; IP: 192.168.30.251, epoch: 2383592
2025/09/02 12:34:49 portmap: [v1] Got PCP response: epoch: 2383592
2025/09/02 12:34:49 netcheck: received STUN packet from x.x.x.x:3478
2025/09/02 12:34:49 netcheck: received STUN packet from [2402:4e00:xxxx:xxxx:xxxxxx]:3478
2025/09/02 12:34:49 portmap: [v1] UPnP reply {Location:http://192.168.31.1:5351/rootDesc.xml Server:MiWiFi/x UPnP/1.1 MiniUPnPd/2.1 USN:uuid:5c324c80-1fff-4fae-997b-abbbf977de89::urn:schemas-upnp-org:device:InternetGatewayDevice:1}, "HTTP/1.1 200 OK\r\nCACHE-CONTROL: max-age=120\r\nST: urn:schemas-upnp-org:device:InternetGatewayDevice:1\r\nUSN: uuid:5c324c80-1fff-4fae-997b-abbbf977de89::urn:schemas-upnp-org:device:InternetGatewayDevice:1\r\nEXT:\r\nSERVER: MiWiFi/x UPnP/1.1 MiniUPnPd/2.1\r\nLOCATION: http://192.168.31.1:5351/rootDesc.xml\r\nOPT: \"http://schemas.upnp.org/upnp/1/0/\"; ns=01\r\n01-NLS: 1754400791\r\nBOOTID.UPNP.ORG: 1754400791\r\nCONFIGID.UPNP.ORG: 1337\r\n\r\n"
2025/09/02 12:34:49 portmap: UPnP meta changed: [{Location:http://192.168.31.1:5351/rootDesc.xml Server:MiWiFi/x UPnP/1.1 MiniUPnPd/2.1 USN:uuid:5c324c80-1fff-4fae-997b-abbbf977de89::urn:schemas-upnp-org:device:InternetGatewayDevice:1}]
2025/09/02 12:34:49 netcheck: portMap done
2025/09/02 12:34:49 netcheck: [v2] attempting to do captive portal detection on interface en0
2025/09/02 12:34:49 netcheck: [v2] 2 available captive portal detection endpoints; trying 2
2025/09/02 12:34:49 netcheck: captivedetection: failed to set IP_BOUND_IF (ifIndex=14): invalid argument
2025/09/02 12:34:49 netcheck: captivedetection: failed to set IP_BOUND_IF (ifIndex=14): invalid argument
2025/09/02 12:34:49 netcheck: DetectCaptivePortal(found=false)
2025/09/02 12:34:49 netcheck: [v1] report: udp=true v6=false v6os=true mapvarydest=true portmap=UMC v4a=x.x.x.x:7651 captiveportal=false derp=900 derpdist=900v4:14ms
2025/09/02 12:34:49 netcheck: GetReport took 770ms; err=<nil>

Report:
	* Time: 2025-09-02T04:34:49.905493Z
	* UDP: true
	* IPv4: yes, x.x.x.x:7651
	* IPv6: no, but OS has support
	* MappingVariesByDestIP: true
	* PortMapping: UPnP, NAT-PMP, PCP
	* CaptivePortal: false
	* Nearest DERP: 
	* DERP latency:
		- tencent-derp: 13.7ms  (derp900, )

2 、使用自建 DERP ，OmitDefaultRegions:False 屏蔽官方节点关闭结果：IPV4 stun 正常，ipv6 正常

3 、使用官方节点，默认配置 OmitDefaultRegions:True 结果：IPV4 stun 正常，ipv6 正常

可能会是什么原因呢？