Visitor
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2 Messages
Intermittent multi-second latency spikes
I'm seeing intermittent multi-second latency spikes and failed connection attempts to external services, specifically on a hop inside Comcast's own
network — not at my modem/router, and not at the destination server. This is NOT a general "my internet feels slow" complaint: I have traceroute/mtr data
pinpointing the exact hop, and it happens while every other hop (including the destination) stays under 15ms.
The spikes are large enough (2-3 seconds of added latency) to break new outbound HTTPS connections from a service I run at home, even though basic
ping tests to the same destination often look completely clean — the problem is specific to new TCP connection setup, not general reachability,
so it's easy to miss with a quick ping check. Could you check for node congestion or a problem on the segment my account's node connects through?
The hop in question is a few hops past my gateway, still within Comcast's network, around the Seattle area (IPs 24.124.128.249, 96.110.44.86, 96.110.34.x below).
EVIDENCE: TCP (port 443) traceroute to a Cloudflare-hosted destination
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Captured 2026-08-29T08:23:14Z, 20 probes per hop, TCP SYN to port 443
(more representative of real application traffic than plain ICMP ping).
Hop 1 192.168.0.1 (my own gateway)
loss 0%, avg 1.1ms, worst 1.3ms
Hop 2 10.27.176.114
loss 0%, avg 11.8ms, worst 15.3ms
Hop 3 68.86.98.253
loss 0%, avg 11.0ms, worst 15.2ms
Hop 4 96.216.61.81
loss 0%, avg 12.5ms, worst 25.9ms
Hop 5 24.124.128.249
loss 0%, avg 11.8ms, worst 20.1ms
Hop 6 24.124.128.249
loss 0%, avg 11.7ms, worst 15.4ms
Hop 7 96.110.44.86 (and several sibling IPs on the same hop: 96.110.34.134,
68.86.93.x, 96.110.44.90/82, 96.110.34.142/130 — normal load-balancing
across parallel links, not a separate problem)
loss 0%, avg 166.8ms, WORST 2089ms, stddev 506ms
>>> THIS IS THE PROBLEM HOP — over 2 full seconds of latency on some
probes, while hops 6 and 8 on either side of it stay under 15ms.
Hop 8 96.110.34.138 (+ sibling IPs, same load-balancing as hop 7)
loss 50%, avg 12.2ms, worst 15.2ms
Hop 9 108.162.243.61 (+ sibling IPs — Comcast/Cloudflare peering boundary)
loss 50%, avg 15.6ms, worst 23.6ms
Hop 10 108.162.243.45 (+ sibling IPs)
loss 0%, avg 12.5ms, worst 21.6ms
Hop 11 162.159.137.232 (Cloudflare/Discord's edge — the destination)
loss 20%, avg 11.5ms, worst 14.3ms
Notes on hops 8-10: these show partial "loss," but each probe returned a different IP (visible as multiple addresses per hop) — that's normal
load-balancing (ECMP) across parallel links at the Comcast/Cloudflare peering boundary, and routers there commonly deprioritize generating the
ICMP replies traceroute relies on without actually dropping real traffic. The meaningful finding is hop 7: a single, consistent latency spike deep
inside Comcast's own network, well before reaching Cloudflare.
ADDITIONAL EVIDENCE: repeated short bursts on a separate occasion
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Earlier capture (same hop, different time window) showed the same pattern:
Hop 6 24.124.128.249
Run 1: avg 269ms, worst 3083ms
Run 2 (minutes later): avg 123ms, worst 2064ms
Every other hop in both runs stayed under 25ms. This is not a one-off blip;
it recurs at this same point in the path across multiple independent
captures, at different times.
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A service I self-host at this address (discord bot) makes routine outbound HTTPS connections to Cloudflare-hosted infrastructure (discord.com). Around the
timestamps of these spikes, new outbound connections fail outright with a connect timeout, while already-established connections and basic ping
checks remain unaffected. This has been observed recurring at various points across multiple days (not a single isolated incident), including one
episode where the affected service was unable to establish an outbound connection at all for roughly 75 seconds straight.
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Please check for congestion, oversubscription, or a hardware issue on the node/segment serving my account (24.19.49.68), particularly around the
segment reached via 24.124.128.249 / 96.110.44.86 / 96.110.34.x. Happy to provide additional traceroute captures, modem signal-level stats, or run
tests at a specific time if that helps your team investigate.



XfinityJamesC
Official Employee
•
3.1K Messages
2 hours ago
Greetings, @user_a1999e! I hope your week has been treating you well. Thanks so much for taking a moment out of your busy day to leave a post on our community forum about these latency spikes. You have definitely come to the right place for assistance.
Can you tell me a little more about what's been happening? Is this an ongoing issue with hop 7, or did it just develop recently? Have you noticed the congestion occurring consistently throughout the day, or does it increase/decrease, depending on when the traceroute is run? Have you noticed any changes since this was originally discovered?
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