Friday, August 29, 2025
Some more notes on the “wireless service unit”
After much experimentation, I found out that the “wireless service unit” the Monopolistic Phone Company sent us to replace the DSL does in fact support multicasting, although it's a bit more pedantic about it than any other router I've encountered so far. The address I used to use, 239.255.0.1, falls into the “administratively scoped” category of multicast addresses, and I picked it because I wanted a multicast address that was scoped. The “wireless service unit” isn't something I fully control, so it rejected that range of multicast addresses. In fact it appeared that it didn't like any multicast address that could, in theory, be routed.
Of course it exhibited different behavior with different blocks. Most of the blocks it would work for just under five minutes, then fail. I found this out by writing some very simple programs—one to send some data once per second to a multicast address, and one to receive the data. I would run the sender on two computers, and the listeners also on the two computers. Both the listeners would receive data from both senders, and then as they approached five minutes, they would only receive multicast packets from the sender running on the same computer.
It was only when I switched to using the one non-routable multicast address block, 224.0.0.0/24, did things Just Work™. 224.0.0.0/24 is categorized as “local subnetwork” and is not routable.
Sigh.
So now I'm able to use the multicast program I was using before, since it was always local to my home network anyway.
Other notes about the “wireless service unit”—it's reporting pages suck. There's the “event report” page, which dumps data like:
| No. | Data/Time | SoureIP | DestinationIP | Proto | Reason |
|---|---|---|---|---|---|
| 1 | 2025/08/… | XXXXXXXXXXXXXXX | XXXXXXXXXXXXXXX | TCP | Generic Discards |
| 2 | 2025/08/… | XXXXXXXXXXXXXXX | XXXXXXXXXXXXXXX | TCP | Generic Discards |
| 3 | 2025/08/… | XXXXXXXXXXXXXXX | XXXXXXXXXXXXXXX | UDP | Generic Discards |
| 4 | 2025/08/… | XXXXXXXXXXXXXXX | XXXXXXXXXXXXXXX | TCP | Generic Discards |
TCP and UDP traffic is being stopped, but what TCP and UDP traffic? No indication, and there's no way to configure what is logged. Lovely.
The other log report is the list of current NAT sessions. It's more useful as it includes source address, destination address, NAT address, protocol, port numbers, and lifetime, but the table itself is capped to a maximum width, so making the browser window wider doesn't show more columns. Horizontal scrolling for the win? I guess? Sigh.
The port-forwarding feature is wonky. On my old router, I could set incoming packets from the Internet to TCP port 22 to be forwarded to my development machine. On the “wireless service unit,” however, setting that up means all traffic to TCP port 22 gets forwarded to my development machine, even on the local network! I mean … yeah … it works, but it's not public traffic that gets forwarded, all traffic gets forwarded. I can work around that but it's annoying.
The “wireless service unit” has also spontaneously rebooted itself a couple of times. Not enough for a pattern to emerge, but enough to be very annoying. And one time it failed to obtain an IPv6 address (which shouldn't change in my opinion but then again, I don't run the Monopolistic Phone Company) and I had to power cycle it to get IPv6 back.
And I can't shake the feeling that it's doing something to my DNS queries, even though I'm running a local DNS server …
