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I am trying to set up a Raspberry Pi 4 as a wlan0 <-> wlan1 router and followed Ingo's excellent guide here:

Access point as WiFi router/repeater with additional WiFi-dongle

Having gone through all the steps on a fresh, updated Buster installation, I've not been able to make this work.

wlan1 happily connects to the internet (I am typing this on the Raspberry Pi 4 in question) and other computers can connect to the access point I set up at wlan0.

However no internet access is happening for computers connected to wlan0.

ifconfig on computers connected to wlan0 indicates that they are somehow picking up an IP address from wlan1's range instead of wlan0's DHCP range.

I'm tearing my few remaining hairs out here. Have gone through the entire process described in Ingo's answer with a fresh install of Buster.

Any help is greatly appreciated!

Additional info:

# Here is my /etc/resolvconf.conf: resolvconf=NO resolv_conf=/etc/resolv.conf dnsmasq_resolv=/var/run/dnsmasq/resolv.conf pdnsd_conf=/etc/pdnsd.conf unbound_conf=/var/cache/unbound/resolvconf_resolvers.conf # My /etc/wpa_supplicant/wpa_supplicant-wlan0.conf: country=GB ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev update_config=1 network={ ssid="Illusionary 2" mode=2 key_mgmt=WPA-PSK psk="connectme" frequency=2412 } # My /etc/wpa_supplicant/wpa_supplicant-wlan1.conf: country=GB ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev update_config=1 network={ ssid="ActualSSID" psk="ActualPW" } # My [email protected]: [Service] ExecStartPre=/sbin/iptables -t nat -A POSTROUTING -o wlan1 -j MASQUERADE ExecStopPost=-/sbin/iptables -t nat -D POSTROUTING -o wlan1 -j MASQUERADE # My /etc/systemd/network/08-wlan0.network: [Match] Name=wlan0 [Network] Address=192.168.4.1/16 IPForward=yes DHCPServer=yes [DHCPServer] DNS=84.200.69.80 1.1.1.1 RouteMetric=200 # My /etc/systemd/network/12-wlan1.network: [Match] Name=wlan1 [Network] Address=192.168.1.199/24 DNS=8.8.8.8 8.8.4.4 DHCP=yes [Route] Gateway=192.168.1.1 Metric=10 [DHPC] RouteMetric=100 # ifconfig output: lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10<host> loop txqueuelen 1000 (Local Loopback) RX packets 12 bytes 600 (600.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 12 bytes 600 (600.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 wlan0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.4.1 netmask 255.255.0.0 broadcast 192.168.255.255 inet6 fe80::dea6:32ff:fe03:2d7c prefixlen 64 scopeid 0x20<link> ether dc:a6:32:03:2d:7c txqueuelen 1000 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 121 bytes 42965 (41.9 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 wlan1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.1.199 netmask 255.255.255.0 broadcast 192.168.1.255 inet6 fe80::76da:38ff:feea:7fcb prefixlen 64 scopeid 0x20<link> ether 74:da:38:ea:7f:cb txqueuelen 1000 (Ethernet) RX packets 6617 bytes 4308027 (4.1 MiB) RX errors 0 dropped 1625 overruns 0 frame 0 TX packets 3264 bytes 481039 (469.7 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 # iwconfig output: wlan0 IEEE 802.11 Mode:Master Tx-Power=31 dBm Retry short limit:7 RTS thr:off Fragment thr:off Power Management:on eth0 no wireless extensions. lo no wireless extensions. wlan1 IEEE 802.11bgn ESSID:"ActualSSID" Nickname:"<WIFI@REALTEK> Mode:Managed Frequency:2.437 GHz Access Point: 80:2A:A8:44:F6:19 Bit Rate:72.2 Mb/s Sensitivity:0/0 Retry:off RTS thr:off Fragment thr:off Power Management:off Link Quality=99/100 Signal level=49/100 Noise level=0/100 Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:0 Missed beacon:0 # route -n output: Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 192.168.1.1 0.0.0.0 UG 10 0 0 wlan1 0.0.0.0 192.168.1.1 0.0.0.0 UG 1024 0 0 wlan1 192.168.0.0 0.0.0.0 255.255.0.0 U 0 0 0 wlan0 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 wlan1 192.168.1.1 0.0.0.0 255.255.255.255 UH 1024 0 0 wlan1`

Updated 2019-10-25:

I've implemented Ingo's suggestions, but so far have had no luck with getting this to work. Access to the internet via wlan1 is (still) working locally, but wlan0 still doesn't connect clients to the internet.

My new /etc/systemd/network/08-wlan0.network: [Match] Name=wlan0 [Network] Address=192.168.4.1/24 IPForward=yes DHCPServer=yes [DHCPServer] DNS=84.200.69.80 1.1.1.1 My new /etc/systemd/network/12-wlan1.network: [Match] Name=wlan1 [Network] DHCP=yes My new ifconfig output: lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10<host> loop txqueuelen 1000 (Local Loopback) RX packets 156 bytes 15032 (14.6 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 156 bytes 15032 (14.6 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 wlan0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.4.1 netmask 255.255.255.0 broadcast 192.168.4.255 inet6 fe80::dea6:32ff:fe03:2d7c prefixlen 64 scopeid 0x20<link> ether dc:a6:32:03:2d:7c txqueuelen 1000 (Ethernet) RX packets 9 bytes 1107 (1.0 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 139 bytes 42957 (41.9 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 wlan1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.1.123 netmask 255.255.255.0 broadcast 192.168.1.255 inet6 fe80::76da:38ff:feea:7fcb prefixlen 64 scopeid 0x20<link> ether 74:da:38:ea:7f:cb txqueuelen 1000 (Ethernet) RX packets 2151 bytes 949342 (927.0 KiB) RX errors 0 dropped 129 overruns 0 frame 0 TX packets 1043 bytes 244850 (239.1 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 My new iwconfig output: wlan0 IEEE 802.11 Mode:Master Tx-Power=31 dBm Retry short limit:7 RTS thr:off Fragment thr:off Power Management:on eth0 no wireless extensions. lo no wireless extensions. wlan1 IEEE 802.11bgn ESSID:"ActualSSID" Nickname:"<WIFI@REALTEK>" Mode:Managed Frequency:2.437 GHz Access Point: 80:2A:A8:44:F6:19 Bit Rate:72.2 Mb/s Sensitivity:0/0 Retry:off RTS thr:off Fragment thr:off Encryption key:****-****-****-****-****-****-****-**** Security mode:open Power Management:off Link Quality=100/100 Signal level=53/100 Noise level=0/100 Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:0 Missed beacon:0 My new route -n output: Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 192.168.1.1 0.0.0.0 UG 1024 0 0 wlan1 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 wlan1 192.168.1.1 0.0.0.0 255.255.255.255 UH 1024 0 0 wlan1 192.168.4.0 0.0.0.0 255.255.255.0 U 0 0 0 wlan0

Updated 2019-10-26, output from 2nd Pi:

iw wlan0 link: Connected to dc:a6:32:03:2d:7c (on wlan0) SSID: Illusionary 2 freq: 2412 RX: 21652487 bytes (154629 packets) TX: 1115276 bytes (7331 packets) signal: -20 dBm tx bitrate: 72.2 MBit/s MCS 7 short GI bbs flags: short preamble short-slot-time dtim period: 2 beacon int: 100 ip addr: 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000 link/ether b8:27:eb:14:2d:b1 brd ff:ff:ff:ff:ff:ff inet 192.168.2.175/24 brd 192.168.2.255 scope global eth0:1 valid_lft forever preferred_lft forever 4: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000 link/ether 00:0b:81:87:b9:bb brd ff:ff:ff:ff:ff:ff inet 192.168.1.114/24 brd 192.168.1.255 scope global wlan0 valid_lft forever preferred_lft forever inet6 fe80::20b:81ff:fe87:b9bb/64 scope link valid_lft forever preferred_lft forever
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  • You write "Having gone through all the steps on a fresh, updated Buster installation" and "Have gone through the entire process described in Ingo's answer twice now, with a fresh install of Stretch both times." and you tagged with raspbian-stretch. Using Stretch doesn't make sense on a RPi 4B so I assume to use a Buster installation. Commented Oct 25, 2019 at 10:12
  • Yep, correct, Buster - I missed the 2nd instance of "Stretch" when I edited the above,. Fixed now! Commented Oct 25, 2019 at 10:27
  • Now it looks good from the given diagnostic output. I can't see any issues yet. Routing table looks good. What is still not working? Do you can connect to the access point? Do you can ping google.com from the RasPi? Commented Oct 25, 2019 at 18:31
  • Pinging google works, and I'm actually writing these comments and updates from the desktop of this Pi4, so no problems with wlan1 as far as I can see. Commented Oct 25, 2019 at 18:38
  • Connections to wlan0 on my Android phone just hang indefinitely. I unfortunately haven't brought my laptop tonight, so I cannot try to connect from that for more detailed diagnostic/routing info. Will try that tomorrow. Commented Oct 25, 2019 at 18:39

1 Answer 1

Reset to default
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You try to run Raspbian Stretch on a Raspberry Pi 4. On the release notes you will find:

2019-06-20:
* Based on Debian Buster
* Support for Raspberry Pi 4 hardware

This means Raspbian Stretch as predecessor from Rasbian Buster does not support Raspberry Pi 4. Before continue troubleshooting please start again with Raspbian Buster.

With your updated info I assume you have used a Raspbian Buster installation. I can see some problems with the configuration. You used in

# My /etc/systemd/network/08-wlan0.network: [Match] Name=wlan0 [Network] Address=192.168.4.1/16 IPForward=yes DHCPServer=yes [DHCPServer] DNS=84.200.69.80 1.1.1.1 RouteMetric=200

The [DHCPServer] section does not define an option RouteMetric=. Look at man systemd.network. You must delete this line. But the main problem is that you use bitmask /16 with ip address 192.168.4.1/16. This selects the whole private subnet 192.168.0.0/16 with 65.536 ip addresses including the subnet for wlan1 (192.168.1.0/24 with 256 ip addresses). This superposition cannot work and may explain the problem you have find with ip addresses. Use ip address 192.168.4.1/24.

# My /etc/systemd/network/12-wlan1.network: [Match] Name=wlan1 [Network] Address=192.168.1.199/24 DNS=8.8.8.8 8.8.4.4 DHCP=yes [Route] Gateway=192.168.1.1 Metric=10 [DHPC] RouteMetric=100

Here are some things wrong. You try to use a static ip address. Why? There is no need. Most problems we see here on this site is using a static ip address because it often conflicts with automatic DHCP network management. In addition you enabled getting an ip address by DHCP with DHCP=yes. This cannot work. I also don't understand why you use additional Sections [Route] and [DHPC]. The latter is a typo. Routing with Metric is managed automatically. Fiddling with manual settings will only confuse the routing table.

The routing table reflects the wrong configuration: two default routes to the same gateway with different Metric makes no sense, a big subnet on wlan0 and a part of it as smaller subnet on wlan1 will not work as intended.

Please just use exactly the configuration I have given in my tutorial. If it then run on your RasPi you can modify it to what you like.

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  • Hi - thanks for responding! Sorry that I'm being a bit slow here - am travelling a lot right now. I'm now running up-to-date buster and am still having trouble after following your guide. Commented Oct 22, 2019 at 17:31
  • @MichaelVirks Comments are only for simple questions but unusable for extended statements as you can see. Yours are all unreadable and I don't read them. Please edit your question and insert what you like to elaborate. There you can also format it. After doing it you can delete your comments. And having a look at the short Tour and visit the Help Center is also a good idea ;-) Commented Oct 22, 2019 at 18:10
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    Sorry - just realised - diagnostic info is now in main post. It's been a long day :-) Commented Oct 22, 2019 at 18:27
  • @MichaelVirks I have updated the answer in respect to your additional configuration info, which is very good and show what's wrong. Commented Oct 25, 2019 at 15:05
  • thanks for that detailed response! Annoyingly still not working, but I've added updated diagnostics info to my question above Commented Oct 25, 2019 at 18:09

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