a653735c

By: ananjiani <ananjiani@noreply.codeberg.org>

fix(steammachine): keep the WiFi radio off so it stops competing with Bluetooth (#351)

## Why

The Steam Machine is **wired and has no use for WiFi**, but its radio shares an antenna with the Bluetooth adapter. NetworkManager scans for networks even while disconnected (`wlp6s0` was `DOWN`/`NO-CARRIER` the whole time), and that 2.4 GHz traffic competes with the controller link — which is already fighting a congested band.

Evidence that the radio was live despite being disconnected: it saw **18 access points** at signal 90-95.

## Measured

With a Pro Controller connected, dropping the radio:

```
                       before      after radio off
  dropped IMU reports   3.2/min     1.5/min
  report gap (delta)    78-105 ms   65-79 ms
  avg_delta             15 ms       11 ms
```

Roughly halves the loss, and the report stream gets denser.

## Ceiling — read this before expecting a fix

This does **not** eliminate the problem. The remainder is neighbouring congestion:

```
ch  1   1 AP   strongest 70
ch  4   3 APs  strongest 82   <- this house's own 2.4 GHz SSIDs
ch  6   3 APs  strongest 95
ch 11   3 APs  strongest 92
```

`hfcl`/neighbour APs on channels 6 and 11 at signal 92-95 are not ours to change. Eliminating the rest needs physical separation: a USB Bluetooth dongle on an extension cable clear of the chassis and TV.

## Change

Adds a oneshot that runs `rfkill block wifi` after `NetworkManager.service`. It is an `rfkill` block rather than just a NetworkManager disconnect, so the phy cannot be woken by a scan.

## Verification

Confirmed safe on the running host before making it declarative: with the WiFi phy soft-blocked, Bluetooth kept working and improved, and `enp5s0` stayed connected.

Co-authored-by: Ammar <ammar.nanjiani@gmail.com>
Reviewed-on: https://codeberg.org/ananjiani/infra/pulls/351

Total

17m45s

Timeline