add maintenance log for 2025-07-31

src/maintenance/2025-07-31.md

@@ -0,0 +1,23 @@
+---
+images:
+- src: 2025-07-31/building-with-celltower-on-roof-dithered.png
+  alt: A photo of a four story builiding with a slanted roof and a cellphone tower on top. There are balconies on each floor, and trees cover the view to the building.
+---
+These random crashes recently were a wifi issue. More specifically an issue with a certain router, having a certain wifi configuration, sending and receiving on a certain range of frequencies, with a certain bandwidth. Which does not seem to be an issue for other devices, but for compost it is.
+
+It was an early realization that network stability varied a lot between different wifis. It took some fiddling until the current setup emerged: Internet → wifi modem → wifi repeater → compost (and back again when responding). Scrolling around and looking for "Archer C7" will tell you a bit about that. It's an old router on top of our neighbors' kitchen shelf which runs on <span class="i-know-what-i-am-doing">OpenWRT</span>, a Linux distribution for modems and routers. It runs reliably(-ish) and was the most stable wireless network we could set up. But sometimes it stops working, and then it's in our neighbors flat, and then both the repeater and compost ask for physical presence. Which is not a huge deal – it's just upstairs! – but this means coordinating access with our neighbors, looking for the right key, maybe planning for some extra time before leaving for work, ...
+
+But in general it worked! In general all of this works, and it worked well enough to let us forget that when compost is connected to this one very specific wifi network it will freeze and become unresponsive after roughly a day. Which to be clear, that's very weird and not something that computers usually do. But it's unclear why exactly that happens, and we accept as just another idiosyncrasy.
+
+It gives us a good reason to keep experimenting though, and most recently (since yesterday) that means changing the network setup: 
+
+```
+sudo nmcli radio wifi off
+sudo nmcli connection celltower up
+```
+
+The topology for an incoming connection now looks like this: Internet → modem → router ⤑ Wireguard tunnel ⤑ compost. compost is not directly connected to a wifi network anymore, but instead receives and sends its traffic through the cellphone network. We still use the same route as before to be able to talk to it from the outside, crossing our home network. But *if* the mobile data connection shows to be stable it could simplify things a bit: no more [redundant port forwarding](https://compost.party/maintenance/#2025-06-30), and compost could move around more easily and still stay in touch.
+
+And it looks like it works? Even though the physical path of each packet is so much more involved now it looks like these packets end up where they should.
+
+Fingers crossed!