I’m having a bizarre networking problem.
the players
the laptop
I have a Framework 13” AMD laptop. It’s running Fedora Linux 40. It has been my desktop daily driver for over a year and has worked nearly flawlessly. It is the canonical repository for all my photos and other documents.
the phone
I have a Pixel 6 smartphone running GrapheneOS. It has been my primary phone since early 2022. I have never noticed any networking problems with it.
the software
I have used Resilio Sync to synchronize files between my phone, one or more servers, and my laptop(s) for longer than I can remember (even back when it was called Bittorrent Sync). This program has made me happy because I can keep my digital world fully in sync without relying on cloud services. It has occasionally behaved strangely (sync is hard!), but it has done what I need silently and unobtrusively, to the point where most of the time I don’t even need to be aware of its existence.
the problem
After I moved to the island place, I started having problems with sync, along with other strange and intermittent networking problems. Since the island internet is actually quite reliable (unless storms take out the six-mile-long fiber optic cable to my house), I started getting really frustrated at these intermittent failures. Then, after many run-ins with the failure, I began to see a pattern:
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Everything would work well until I turned on sync on my phone (I leave it off most of the time, as it tends to degrade battery life). Usually, that would be because I had taken pictures and wanted to incorporate them into a column.
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I would look for the pictures on my laptop, and they wouldn’t be there.
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I would try other ways to get the pictures from my phone to the laptop
- use Signal to send them to a “note to self” but the message would never arrive
- email them to myself (the email server, the phone, and the laptop are all on the same network and work flawlessly 99.999+% of the time); the email message would show up in my inbox, but never finish downloading
- I would try to upload the pictures to my personal, private pastebin but the upload would stall partway through
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I would start diagnosing the network problems
- if I checked fast.com on my laptop, it would be down to a few kilobytes per second; ugh
- network operations would be really flaky, but I couldn’t tell whether that was just from it being too slow or if there was, say, another kind of packet loss going on
- if I checked fast.com on any other device, it would show degraded service but not nearly so bad (200-500 MBps)
- starting or stopping Sync on the phone or laptop had no effect on network performance
- if I tried to change networks on the laptop from the 2.4GHz band to the 5GHz band or vice-versa, the laptop would fail to connect
- stopping and re-starting WiFi on the laptop wouldn’t help
- rebooting the laptop (or even powering it off and back on) wouldn’t help, but would sometimes result in not being able to connect to WiFi at all
- turning the Zyxel fiber modem/WiFi access point off and back on again would often result in no internet access at all
- repeating the power cycling of the modem would result in a full recovery of the network at near gigabit speeds
other weirdnesses
If I’m on my phone on another network (say, cellular data) and I start Sync, everything works fine. Sync also seems to be working fine between my laptop and a local server that’s running Sync.
This whole setup ran for over a year with no problem when there wasn’t a Zyxel modem/access point in the loop.
In short, starting Resilio Sync on my phone would result in a disruption of the connection between my laptop and the internet, but not (obviously) change in the behavior of other devices. Only restarting the modem/access point — usually twice! — restores access from my laptop.
Now, any time a non-privileged client can render other devices on the network inoperable even when said client is no longer running is a serious security issue. The flaw is almost certainly in the modem software, but I can’t imagine getting anyone to take it seriously. How does Resilio Sync trigger the bug? How come it only affects the laptop? What has twoprops been smoking?
It’s a strange one by any measure. I hate to give up Resilio Sync but obviously it’s unusable in this situation.
I suppose once things settle down more here, I’ll leave the Zyxel doing the fiber interface (I doubt my ISP would support my replacing it) and set up an independent WiFi access point. I probably need to do that anyway for proper firewalling. But I’ll have to ask in the Resilio Sync forums and any Zyxel support venues I can find to see if anyone else has noticed anything remotely similar.
—2p