Source: https://mayphus.org/ipv4-vs-ipv6/
Title: IPv4 vs IPv6: three days of measuring my home link to an overseas server
Metadata: {"category":"note","date":"2026-10-28T00:00:00Z","id":"ipv4-vs-ipv6","kind":"article","language":"en","locale":"en","route":"/ipv4-vs-ipv6/","slug":"ipv4-vs-ipv6","tags":["networking","measurement","operations-record"],"type":"article"}

My home router keeps a long-lived connection to a small server overseas. On IPv4 it kept dropping out, so I logged it, switched the link to IPv6, and kept logging for three days. Here is what the data shows.

![Share of failed checks, IPv4 vs IPv6](/ipv4-vs-ipv6/ipv4-vs-ipv6.png)

## How I measured

- A script on the router fetched a tiny page through the overseas link every 10 to 15 seconds and recorded success and response time.
- Each check also fetched a domestic site as a control, so I could tell a problem with the overseas link from a problem with my home internet.
- A second script ran a broader check every 2 minutes, including a plain TCP connection to the server.
- IPv4: one evening, 25 Oct 21:12 to 23:32 (about 2 hours, 459 checks).
- IPv6: 25 Oct 23:36 to 28 Oct 17:43 (about 66 hours, 14,823 checks).
- An "outage" is one or more failed checks in a row while the domestic site still worked.

## Results

| | IPv4 | IPv6 |
|---|---|---|
| Failed checks | 175 of 459 (38%) | 56 of 14,823 (0.38%) |
| Outages | 38 (about 19 per hour) | 37 (about 0.6 per hour) |
| Typical gap between outages | about 3 minutes | about 1 to 1.5 hours |
| Typical outage length | 40 to 65 seconds | 5 to 35 seconds |
| Longest outage | about 11 minutes | about 3 minutes (right after the switch) |
| Share of time down | about 37% | about 0.2% |
| Response time when working (median / 95th percentile) | 0.73 s / 1.65 s | 0.72 s / 0.98 s |
| 2-minute checks failed | 29% of 48 | 0.3% of 1,890 |

The domestic control site never failed in either period, and plain TCP connections to the server succeeded 170 out of 170 times. So the home internet was fine; it was the long-lived connection over IPv4 that kept stalling.

## IPv6 day by day

| Day | Outages | Notes |
|---|---|---|
| 26 Oct | 14 | One lasted about 1 to 1.5 minutes; the rest were single failed checks |
| 27 Oct | 14 | All single failed checks |
| 28 Oct (to 17:43) | 4 | The one longer outage (13:59) was my home line, not the link |

After the first 20 minutes on IPv6, almost every outage was a single failed check at an irregular time, with no upward trend over the three days.

## Takeaways

- On IPv4 the link dropped out at irregular times every 1 to 3 minutes and was down about a third of the evening. "Every minute for a few seconds" undersells it: a typical dropout lasted most of a minute.
- On IPv6 it dropped about 14 times a day, almost always for half a minute or less, and response times got more consistent.
- For this link, switching to IPv6 was the single change that fixed it.

## Limits

- Checks ran every 10 to 15 seconds, so outage lengths are accurate to about ±15 seconds and dropouts shorter than about 5 seconds don't show up.
- The IPv4 data covers one evening only, so it can't say whether IPv4 was that bad at other times of day.