DHCP reponse lost on AP Mode Flint AX1800 Firmware 4.8.3

Routers
1

I have a AX1800 for almost more than a year and it had been working great.

I have it in AP mode, and my main router is another AX1800. I set both routers to the same SSID to allow for roaming. Both are using WPA2/WPA3 mixed mode on oth 2.4GHz and 5GHz.

I noticed that once upgraded to 4.8.3 on the AP, when switching from the router to the AP, connection will be lost on the connecting device. Based on logs and tcp dump, it seems that it has trouble getting DHCP:

Log on main router:

Sun Apr 26 14:20:43 2026 daemon.info dnsmasq-dhcp[11807]: DHCPDISCOVER(br-lan) 7a:94:42:62:18:43
Sun Apr 26 14:20:43 2026 daemon.info dnsmasq-dhcp[11807]: DHCPOFFER(br-lan) 192.168.8.49 7a:94:42:62:18:43
Sun Apr 26 14:20:47 2026 daemon.info dnsmasq-dhcp[11807]: DHCPDISCOVER(br-lan) 7a:94:42:62:18:43
Sun Apr 26 14:20:47 2026 daemon.info dnsmasq-dhcp[11807]: DHCPOFFER(br-lan) 192.168.8.49 7a:94:42:62:18:43
Sun Apr 26 14:20:48 2026 daemon.info hostapd: wlan1: STA cc:f4:11:af:a4:f9 IEEE 802.11: disconnected due to excessive missing ACKs
Sun Apr 26 14:20:48 2026 daemon.notice hostapd: wlan1: AP-STA-DISCONNECTED cc:f4:11:af:a4:f9
Sun Apr 26 14:20:49 2026 daemon.info dnsmasq-dhcp[11807]: DHCPDISCOVER(br-lan) cc:f4:11:af:a4:f9
Sun Apr 26 14:20:49 2026 daemon.info dnsmasq-dhcp[11807]: DHCPOFFER(br-lan) 192.168.118.47 cc:f4:11:af:a4:f9
Sun Apr 26 14:20:55 2026 daemon.info dnsmasq-dhcp[11807]: DHCPDISCOVER(br-lan) 7a:94:42:62:18:43
Sun Apr 26 14:20:55 2026 daemon.info dnsmasq-dhcp[11807]: DHCPOFFER(br-lan) 192.168.8.49 7a:94:42:62:18:43

tcpdump on device:

14:20:43.538694 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 7a:94:42:62:18:43, length 306
14:20:47.903799 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 7a:94:42:62:18:43, length 304
14:20:55.407905 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 7a:94:42:62:18:43, length 304
14:21:05.260312 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 7a:94:42:62:18:43, length 306

No logs show up on the AP itself.

Only after about 3-4mins, do I get a DHCPACK on the router and tcpdump will finally capture a DHCP response. The connection will work fine after that, but the same will happen after switching to the router and back the the AP again.

It seems like something is losing the DHCPOFFER sent by the main router.

This happens even with all default settings other than using Access Point Mode, WPA2+WPA3, and changing the SSID. Using only WPA2 also reproduces the problem.

Once downgraded to 4.6.8 everything works well again.

2

Hi

Thanks for your report.

Could you please follow the guide and share both routers with us via GoodCloud so we can check it remotely?

Kindly note to send us the MAC address and the router password via private message so we can access it

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4

Both are connected and DMed the details!

I kept the AP on 4.6.8 for now or my home setup would be sort of unusable, but upgrading to 4.8.3, both automatic and local upload upgrades reproduces it everytime.

5

In this case, it seems difficult to troubleshoot the issue remotely.

Could you help upgrade the firmware to 4.8.3 again, reproduce the issue and, on the AX1800 acting as an AP, capture packets on the following interfaces at the same time?

# Install the tcpdump
opkg update && opkg install tcpdump

# Uplink interface
tcpdump -i eth0 -n -e 'udp and (port 67 or port 68)' -w /tmp/eth0_dhcp.pcap 

# Wi-Fi interfaces
## 2.4 GHz
tcpdump -i wlan0 -n -e 'udp and (port 67 or port 68)' -w /tmp/wlan0_dhcp.pcap 

## 5 GHz
tcpdump -i wlan1 -n -e 'udp and (port 67 or port 68)' -w /tmp/wlan1_dhcp.pcap 

# Bridge interface
tcpdump -i br-lan -n -e 'udp and (port 67 or port 68)' -w /tmp/br_dhcp.pcap

After that, please export the logs from both the main router and the AP router, and send them to us via private message along with the packet captures.