更新 1发布如下。
我们家里有有线互联网服务(Comcast/Xfinity)。我有一个自有的Netgear CM400 电缆调制解调器。调制解调器连接到无线路由器,为家中的设备提供有线和无线连接。
我正在使用速度测试网和fast.com测量互联网连接速度的服务。
当直接连接到调制解调器网络端口时,我测量的连接速度约为 240 Mbps。但是,一旦通过路由器连接,速度就会急剧下降。特别是通过 WiFi,我说的急剧下降是指速度低于 1 Mbps。有趣的是,上传速度始终高于下载速度。
很长一段时间我都有On Networks N150R Wireless-N 路由器连接。随着时间的推移,连接速度变得如此缓慢。在尝试排除故障时,我注意到,当对调制解调器和路由器进行电源循环时,速度会短暂增加,但随后又恢复到缓慢的速度。
因为直连速度很快,所以我以为是路由器的问题。
于是,我选了一张老一点的,eHome EH100 Wireless-G 路由器并替换了 OnNetwork。但速度仍然很慢。
作为最后的手段,我订购了一个Linksys AC1000 无线-AC 路由器更换 eHome 路由器。我以为问题出在老式廉价路由器上,我原本以为新路由器的连接速度会非常快。但令我失望的是,速度虽然有所提高,但仍保持在个位数的低位。
这让我现在怀疑问题是否真的出在调制解调器本身。我不知道这是怎么回事,也不确定事情是如何运作的,但是一旦调制解调器连接到路由器,路由协议是否会导致调制解调器的下行链路连接出现问题?
请注意,所有 3 个路由器都是 10/100 Mbps 路由器,而不是 GigE。笔记本电脑和调制解调器是 GigE,这就是为什么我可以测量直接连接上的 240 Mbps。
连接到两个设备的管理服务器的详细信息:
CM400 调制解调器指示电缆连接良好。两个方向的电缆传输功率水平都在 Netgear 建议的范围内。查看事件日志文件显示了一些 T3 超时事件,但据我所知,这个频率是正常的(是这样吗?):
Time Priority Description
Time Not Established Critical (3) No Ranging Response received - T3 time-out
Aug 21 16:53:05 2020 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Sep 3 09:31:12 2020 Critical (3) No Ranging Response received - T3 time-out
Sep 3 09:34:10 2020 Critical (3) SYNC Timing Synchronization failure - Loss of Sync
Sep 3 09:38:11 2020 Critical (3) No Ranging Response received - T3 time-out
Sep 9 12:08:05 2020 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Sep 10 00:46:58 2020 Warning (5) RCS Partial Service
Sep 15 08:47:44 2020 Critical (3) Unicast Ranging Received Abort Response - initializing MAC
Sep 15 08:47:44 2020 Critical (3) No Ranging Response received - T3 time-out
Sep 15 09:00:22 2020 Critical (3) Unicast Ranging Received Abort Response - initializing MAC
Sep 15 09:00:23 2020 Critical (3) No Ranging Response received - T3 time-out
Sep 16 16:25:04 2020 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Sep 16 16:25:05 2020 Warning (5) RCS Partial Service
Sep 19 07:18:15 2020 Critical (3) No Ranging Response received - T3 time-out
Sep 19 07:18:31 2020 Critical (3) Unicast Ranging Received Abort Response - initializing MAC
Sep 19 07:18:31 2020 Critical (3) No Ranging Response received - T3 time-out
Sep 19 07:19:51 2020 Critical (3) Unicast Ranging Received Abort Response - initializing MAC
Sep 19 07:19:51 2020 Critical (3) No Ranging Response received - T3 time-out
Sep 19 07:20:09 2020 Critical (3) Unicast Ranging Received Abort Response - initializing MAC
Sep 19 07:20:09 2020 Critical (3) No Ranging Response received - T3 time-out
Sep 19 07:20:28 2020 Critical (3) Unicast Ranging Received Abort Response - initializing MAC
Sep 19 07:20:28 2020 Critical (3) No Ranging Response received - T3 time-out
Sep 19 07:20:48 2020 Critical (3) Unicast Ranging Received Abort Response - initializing MAC
Sep 19 07:20:48 2020 Critical (3) No Ranging Response received - T3 time-out
Sep 19 07:21:25 2020 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Sep 19 07:33:39 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out
Sep 24 21:06:08 2020 Warning (5) Lost MDD Timeout
Time Not Established Critical (3) No Ranging Response received - T3 time-out
Sep 28 12:19:47 2020 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Sep 28 13:05:36 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out
Sep 29 20:27:31 2020 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Time Not Established Critical (3) No Ranging Response received - T3 time-out
Sep 30 12:53:58 2020 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Time Not Established Critical (3) No Ranging Response received - T3 time-out
Oct 1 07:07:08 2020 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Time Not Established Critical (3) No Ranging Response received - T3 time-out
Oct 1 20:38:34 2020 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Time Not Established Critical (3) No Ranging Response received - T3 time-out
Oct 2 02:46:51 2020 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Oct 2 02:59:02 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out
在 Linksys 路由器的管理服务器中,我应用了 ping 测试来www.comcast.com:
PING 2600:1401:2000:18b::20b(2600:1401:2000:18b::20b) 32 data bytes
40 bytes from 2600:1401:2000:18b::20b: icmp_seq=1 ttl=60 Time=16.3 ms
40 bytes from 2600:1401:2000:18b::20b: icmp_seq=2 ttl=60 time=9.86 ms
40 bytes from 2600:1401:2000:18b::20b: icmp_seq=3 ttl=60 time=22.3 ms
40 bytes from 2600:1401:2000:18b::20b: icmp_seq=4 ttl=60 Time=11.7 ms
40 bytes from 2600:1401:2000:18b::20b: icmp_seq=5 ttl=60 time=11.4 ms
--- 2600:1401:2000:18b::20b data statistics ---
5 Packets transmitted, 5 received, 0% Packet loss, Time 4016ms
rtt min/avg/max/mdev = 9.860/14.348/22.380/4.569 m
知道该问题可能是什么原因造成的,以及如何解决它?
如果您认为有更好的 SE 网站可以提出此问题,请告诉我。
更新 1:
在与康卡斯特代表交谈后,她得出结论,问题出在调制解调器本身,他们声称已经从她这边进行了一些诊断,需要更换或修复。一个限制是这不是租用的(也不是特别批准的)调制解调器,所以她无法进行进一步的远程测试。
但我确实经历了以下事情:
- 用过的speedtest.xfinity.com作为测试服务器
- 将测试笔记本电脑直接连接到调制解调器
- 检查调制解调器管理服务器中的 SNR 和信号强度
- 将调制解调器恢复出厂设置(使用重置按钮并使用管理服务器)
- 最后,将调制解调器移至前电缆分配器(因此它通过单根同轴电缆直接连接到墙壁)
我观察到的情况如下:
重启调制解调器后,连接速度超过 200Mbps,正如预期的那样。然而,随着时间的推移,速度开始严重下降。20 分钟后,速度又恢复到缓慢的速度。
每当我更换连接到调制解调器的设备(即更换路由器或切换到笔记本电脑)时,我都需要重新启动调制解调器才能连接到互联网。因此,每次切换设备后,测量速度都很好。只是过了一段时间后速度才会下降。这个事实让我最初相信直接连接 PC 是没问题的。
在每个交换机上重新启动调制解调器是正常的吗?为什么连接到路由器的 LAN 端口时不需要这样做?
我会尝试更换调制解调器,看看能否修好。如果没有,那么问题肯定出在同轴电缆或街道到家庭连接本身。