I have Comcast Xfinity in the San Francisco Bay Area. I've been experiencing intermittent connectivity drops for several months, and have finally gotten around this weekend to investigating a little more deeply. The equipment I'm using is listed below.
Modem: Arris Surfboard SB6141
WiFi Router: Netgear WNDR3700v2
I always use wifi at home, never the wired connection directly into the modem. The behavior I see is that I'll be working online, everything is chugging along just fine, and then the connection drops for ~1-5 seconds and then reconnects. When I'm working from home, I have a VPN client open, so I can see in real-time when the connection drops and when it re-connects because the client will show me a pop-up message when the connectivity changes. During this time, websites are unreachable.
This morning I had a couple of terminals open and I was pinging google.com and my wifi router to try to see if the culprit is the signal from the router, or upstream of the router. I think the evidence shows that it's not the router. Here's what I saw during one such instance of connectivity loss this morning.
MacBook-Pro:~ user$ ping -t 100 google.com PING google.com (220.127.116.11): 56 data bytes Request timeout for icmp_seq 0 Request timeout for icmp_seq 1 92 bytes from 18.104.22.168: Destination Host Unreachable Vr HL TOS Len ID Flg off TTL Pro cks Src Dst 4 5 00 5400 08c1 0 0000 3f 01 1554 192.168.2.3 22.214.171.124 Request timeout for icmp_seq 2 Request timeout for icmp_seq 3 Request timeout for icmp_seq 4 Request timeout for icmp_seq 5
Meanwhile my router was returning pings the whole time.
MacBook-Pro:~ user$ ping -t 100 192.168.2.1 PING 192.168.2.1 (192.168.2.1): 56 data bytes 64 bytes from 192.168.2.1: icmp_seq=0 ttl=64 time=0.990 ms 64 bytes from 192.168.2.1: icmp_seq=1 ttl=64 time=1.204 ms 64 bytes from 192.168.2.1: icmp_seq=2 ttl=64 time=30.186 ms 64 bytes from 192.168.2.1: icmp_seq=3 ttl=64 time=1.741 ms 64 bytes from 192.168.2.1: icmp_seq=4 ttl=64 time=2.641 ms 64 bytes from 192.168.2.1: icmp_seq=5 ttl=64 time=1.126 ms 64 bytes from 192.168.2.1: icmp_seq=6 ttl=64 time=2.516 ms 64 bytes from 192.168.2.1: icmp_seq=7 ttl=64 time=5.234 ms 64 bytes from 192.168.2.1: icmp_seq=8 ttl=64 time=3.084 ms
I've pasted below some data from my modem from http://192.168.100.1.
|DOCSIS Downstream Channel Acquisition||Done|
|Establish IP Connectivity using DHCP||Done|
|Establish Time Of Day||Done|
|Transfer Operational Parameters through TFTP||Done|
|Cable Modem Status||Operational|
|Initialize Baseline Privacy||Done|
|Frequency||627000000 Hz||633000000 Hz||639000000 Hz||645000000 Hz||651000000 Hz||657000000 Hz||663000000 Hz||669000000 Hz|
|Signal to Noise Ratio||38 dB||39 dB||39 dB||38 dB||39 dB||39 dB||39 dB||39 dB|
|Power Level||4 dBmV||4 dBmV||4 dBmV||4 dBmV||4 dBmV||4 dBmV||4 dBmV||4 dBmV|
|Frequency||36700000 Hz||30300000 Hz||23700000 Hz||17300000 Hz|
|Ranging Service ID||12616||12616||12616||12616|
|Symbol Rate||5.120 Msym/sec||5.120 Msym/sec||5.120 Msym/sec||5.120 Msym/sec|
|Power Level||44 dBmV||45 dBmV||45 dBmV||45 dBmV|
|Upstream Modulation|| QPSK
|Total Unerrored Codewords||59942129||58666486||58674658||58657397||58647740||58648935||58645702||58650305|
|Total Correctable Codewords||11||9||23||37||63||151||115||14|
|Total Uncorrectable Codewords||1472||1459||1464||1435||1493||1402||1419||1494|
Does anyone have a recommendation about how to proceed? I'm not entirely sure where to go from here.
It occurred again about 15 minutes after I made this post while I was poking around the forum. I had a terminal open - this time I was pinging google.com, 192.168.2.1, and 192.168.100.1. The connectivity dropped for about 10 seconds. During that time, pings to both google.com and 192.168.100.1 timed out. Pings to 192.168.2.1 were returned as usual. Checking my modem logs, I see the following.
|Feb 09 2020 08:45:17||3-Critical||R02.0||No Ranging Response received - T3 time-out;CM-MAC=20:3d:66:09:f2:f3;CMTS-MAC=00:01:5c:62:ac:4a;CM-QOS=1.1;CM-VER=3.0;|
The signal stats were o/k at that snapshot in time. For a test, does a computer hardwired directly to the WNDR3700v2 router with an ethernet cable have the same problem ?
As a second test, does a computer hardwired directly to the 6141 cable modem have the same problem ?