ap: parallel 2.4GHz AP (hostapd-2g) on the Linksys WUSB6300v2 dongle

Second radio (wlxd8ec5e2faa8c, RTL8822BU/rtw88), same VanLink SSID+PSK,
ch6 HT20, bridged into br0 next to the 5GHz AP. Runs as its own hostapd
instance + own watchdog so a USB wedge on one radio never darkens the
other; van-ap-watchdog now takes conf path + unit name as args (defaults
unchanged). rtw88.conf disables deep power-save (rtw89 gotcha analog)
and the driver's USB2->3 self-upgrade (USB3 noise in the 2.4GHz band —
note: dongle currently sits in a USB3 port, so it still enumerates
SuperSpeed; move to a USB2 port if 2.4GHz range disappoints).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

ap/11-van-ap-2g.network

@@ -0,0 +1,11 @@
+[Match]
+Name=wlxd8ec5e2faa8c
+
+[Link]
+RequiredForOnline=no
+
+# No IP here: like the 5GHz AP wlan (10-van-ap.network), this is a br0 member —
+# hostapd-2g adds it to the bridge after putting the radio into AP mode. networkd
+# must NOT enslave it; this file only brings the link up.
+[Network]
+ConfigureWithoutCarrier=yes

ap/hostapd-2g.conf

@@ -0,0 +1,25 @@
+interface=wlxd8ec5e2faa8c
+# Second, independent hostapd instance (hostapd-2g.service) — 2.4GHz band of the same
+# VanLink network, bridged into the same br0 segment as the 5GHz AP and the wired port.
+# Separate process on purpose: a USB wedge on one radio must never take down the other.
+bridge=br0
+# Same ctrl dir as the 5GHz AP — sockets are per-interface, hostapd_cli/watchdog use -i.
+ctrl_interface=/var/run/hostapd
+driver=nl80211
+# Same SSID + PSK as 5GHz: dual-band clients pick a band themselves, 2.4-only IoT
+# devices just join. Rename here (e.g. VanLink-2G) if band pinning is ever needed.
+ssid=VanLink
+country_code=CA
+ieee80211d=1
+hw_mode=g
+channel=6
+wmm_enabled=1
+# HT20 only — 40MHz in 2.4GHz overlaps most of the band and coexistence would force
+# it back to 20MHz near any neighbor anyway.
+ieee80211n=1
+ht_capab=[LDPC][SHORT-GI-20]
+auth_algs=1
+wpa=2
+wpa_passphrase=1foot11foot11
+wpa_key_mgmt=WPA-PSK
+rsn_pairwise=CCMP

ap/hostapd-2g.service

@@ -0,0 +1,15 @@
+[Unit]
+Description=VanLink 2.4GHz AP (hostapd on wlxd8ec5e2faa8c, RTL8822BU)
+# Same USB re-enumeration hazards as the 5GHz AP (see hostapd-restart.conf for the
+# full story): never stop retrying, and back off a few seconds so the USB device can
+# re-enumerate before the next attempt.
+StartLimitIntervalSec=0
+After=network.target
+
+[Service]
+ExecStart=/usr/sbin/hostapd /etc/hostapd/hostapd-2g.conf
+Restart=always
+RestartSec=5
+
+[Install]
+WantedBy=multi-user.target

ap/rtw88.conf

@@ -0,0 +1,10 @@
+# 2.4GHz AP dongle (Linksys WUSB6300 v2, RTL8822BU, rtw88_8822bu).
+# Deep power-save has no business on an always-on AP radio — same reasoning as the
+# rtw89 disable_ps_mode gotcha on the 5GHz dongle (rtw89.conf).
+options rtw88_core disable_lps_deep=Y
+# Don't let the driver switch a USB2-enumerated dongle up to USB3: USB3 signalling
+# radiates broadband noise right across the 2.4GHz band, and HT20 rates fit in USB2
+# easily. NOTE: this only blocks the driver's own USB2->3 switch — a dongle sitting in
+# a USB3 port still enumerates at SuperSpeed (it currently does); move it to a USB2
+# port if 2.4GHz range/interference ever looks poor.
+options rtw88_usb switch_usb_mode=N

ap/van-ap-unmanaged.conf

@@ -1,4 +1,4 @@
 [keyfile]
-# The AP wlan and the wired LAN port are both owned by systemd-networkd/hostapd
-# (bridged into br0), so NetworkManager must not touch either of them.
-unmanaged-devices=interface-name:wlxc83a35a4ee55;interface-name:enx00e04c331140
+# The AP wlans (5GHz + 2.4GHz) and the wired LAN port are all owned by
+# systemd-networkd/hostapd (bridged into br0), so NetworkManager must not touch them.
+unmanaged-devices=interface-name:wlxc83a35a4ee55;interface-name:wlxd8ec5e2faa8c;interface-name:enx00e04c331140

ap/van-ap-watchdog

@@ -18,6 +18,10 @@ exited, so Restart=always never fired. The link check catches exactly that. If t
 unhealthy for `fail_threshold` checks in a row, it clears any failed state and restarts
 hostapd. If the interface is simply gone (mid re-enumeration) it waits — there is
 nothing to restart onto, and Restart=always reclaims it when it reappears. Stdlib only.
+
+Usage: van-ap-watchdog [hostapd.conf path] [systemd unit]
+Defaults watch the 5GHz AP (/etc/hostapd/hostapd.conf, unit hostapd); the 2.4GHz
+instance (van-ap-watchdog-2g.service) passes hostapd-2g.conf + hostapd-2g.
 """
 
 import re
@@ -26,7 +30,8 @@ import sys
 import time
 from pathlib import Path
 
-HOSTAPD_CONF = "/etc/hostapd/hostapd.conf"
+HOSTAPD_CONF = sys.argv[1] if len(sys.argv) > 1 else "/etc/hostapd/hostapd.conf"
+HOSTAPD_UNIT = sys.argv[2] if len(sys.argv) > 2 else "hostapd"
 CTRL_DIR = "/var/run/hostapd"
 INTERVAL = 15          # seconds between health checks (backstop cadence, not first response)
 FAIL_THRESHOLD = 2     # consecutive bad checks before restarting (debounces re-enum blips)
@@ -98,15 +103,15 @@ def ap_enabled(ifname):
 
 
 def recover(ifname):
-    log(f"AP {ifname} not beaconing — clearing failed state and restarting hostapd", "warn")
+    log(f"AP {ifname} not beaconing — clearing failed state and restarting {HOSTAPD_UNIT}", "warn")
     # reset-failed first in case some other path parked the unit in a failed state;
     # harmless when it isn't.
-    subprocess.run(["systemctl", "reset-failed", "hostapd"],
+    subprocess.run(["systemctl", "reset-failed", HOSTAPD_UNIT],
                    capture_output=True, text=True)
-    r = subprocess.run(["systemctl", "restart", "hostapd"],
+    r = subprocess.run(["systemctl", "restart", HOSTAPD_UNIT],
                        capture_output=True, text=True)
     if r.returncode != 0:
-        log(f"hostapd restart returned {r.returncode}: {r.stderr.strip()}", "warn")
+        log(f"{HOSTAPD_UNIT} restart returned {r.returncode}: {r.stderr.strip()}", "warn")
 
 
 def main():

ap/van-ap-watchdog-2g.service

@@ -0,0 +1,13 @@
+[Unit]
+Description=VanLink 2.4GHz AP watchdog — recover hostapd-2g if the radio wedges after a USB glitch
+After=hostapd-2g.service
+Wants=hostapd-2g.service
+
+[Service]
+Type=simple
+ExecStart=/usr/local/sbin/van-ap-watchdog /etc/hostapd/hostapd-2g.conf hostapd-2g
+Restart=always
+RestartSec=5
+
+[Install]
+WantedBy=multi-user.target