Update as of May 22nd 2023: 

The following official firmware has fixed the DHCP issue mentioned in this thread.

ER605 V1_1.3.0 Official Firmware (Released on May 17th, 2023)

Note: the firmware is applied to ER605 V1 and V1.60.

ER605 V2_2.1.2 Official Firmware (Released on Feb 14th, 2023)

Note: the firmware is applied to ER605 V2 and V2.60.

ER7206 V1_1.3.0 Official Firmware (Released on Mar 28th, 2023)

Note: the firmware is applied to ER7206 V1 and V1.60.

ER8411 V1_1.0.3 Official Firmware (Released on Mar 17th, 2023)

Note: the firmware is applied to ER8411 V1 and V1.60.

ER7212PC V1_1.0.3 Official Firmware (Released on Mar 21st, 2023)

As the official firmware has been released to fix the issue, this thread will be locked to stop updating.

Any further issues or concerns, please feel free to Start a New Thread from HERE.

To get better assistance, you may check Tips For Efficiently Reporting an Issue In The Community.

Update as of Mar 8th 2023:

1. Update the Beta firmware of ER7212PC v1, which fixed all DHCP issues and added some new features.

ER7212PC(UN)_V1_1.0.3 Build 20230228 (Beta)

Beta Release Note:

1) Fixed all DHCP issues based on the official firmware 1.0.2 Build 20230202.

2) Add support for modifying port PVID and optimized stability of the device.

3) Cloud Access is available for the above ER7212PC 1.0.3 Beta.

4) You may need to manually upgrade the upcoming official 1.0.3 firmware once you install the above 1.0.3 Beta.

2. Add note that ER605 v1 and ER7206 v1 have a new Beta firmware for trial, which fixed all DHCP issues and added some new features.

ER7206 V1_1.2.3 Beta Firmware For Trial (Released on Feb 28th, 2023)

ER605 V1_1.2.3 Beta Firmware For Trial (Released on Feb 28th, 2023)

Kind Note:

If you don't need the new features added in the above 1.2.3 Build 20230224 (Beta), it's okay to stay with the earlier Build 20230208 (Beta).

Notes:

(1) Please be sure you have read the Beta Test Agreement before proceeding!

(2) The above Beta has added the fix for the DHCP Reservation issue mentioned HERE.

Update as of Feb 21st 2023:

Add beta firmware for ER8411 v1 and ER7212PC v1 to fix all DHCP issues.

ER8411(UN)_V1_1.0.2 Build 20230214 (Beta)

Beta Release Note:

Fixed all DHCP issues based on the official firmware 1.0.2 Build 20230115.

Notes:

(1) Please be sure you have read the Beta Test Agreement before proceeding!

(2) The above Beta has added the fix for the DHCP Reservation issue mentioned HERE.

Edit on Feb 23rd 2023: add note that Cloud Access is unavailable for the above ER7212PC Beta.

New ER7212PC Beta will be provided soon to add Cloud Access availability. Please wait patiently.

Update as of Feb 14th 2023:

Here are the new solutions to resolve the new DHCP issues we recently received in the community, including

1. DHCP Server failed to assign an IP address when a large number of clients make DHCP requests at the same time.

2. DHCP server failed to assign the correct reserved IP address to some clients.

Beta Firmware Download:

ER605(UN)_v1_1.2.2_Build 20230208 (Beta)

Beta Release Note:

Fixed all DHCP issues based on the official firmware 1.2.1 Build 20220512.

ER7206(UN)_v1_1.2.3_Build 20230208 (Beta)

Beta Release Note:

Fixed all DHCP issues based on the official firmware 1.2.3 Build 20221104.

ER8411(UN)_V1_1.0.2 Build 20230214 (Beta)

Beta Release Note:

Fixed all DHCP issues based on the official firmware 1.0.2 Build 20230115.

Notes:

(1) Please be sure you have read the Beta Test Agreement before proceeding!

(2) The above Beta has added the fix for the DHCP Reservation issue mentioned HERE.

For ER605 V2, please check for the official firmware below to fix the DHCP issue.

ER605 V2_2.1.2 Official Firmware (Released on Feb 14th, 2023)

Note: the firmware is applied to ER605 V2 and V2.60.

As always, thank you for working with our support engineers to address the issue with great cooperation.

And thank you all for your great patience when we're trying to figure out the issue and fix it!

Update as of Jan 30th 2023:

Thank you all for your feedback on this forum to let us know that the DHCP issues are still existed, and more importantly, thanks for our loyal users who worked with our support engineers to figure out the issue with great cooperation.

Here are the updates of the Beta firmware to fix all the DHCP issues that have been located, including

• DHCP Server failed to assign valid IP addresses to some clients. Reported Here.
• Different clients have duplicated IP address on the Omada Controller. Reported Here.
• Offline wireless clients were still shown up in Clients list and reported as connected to the Omada Router. Reported Here.

(Note that ER605 v2 ONLY have the last DHCP issue mentioned above, which is a mis-report by the router.)

Beta Firmware Download:

ER605(UN)_v1_1.2.2_Build 20230118 (Beta)

Beta Release Note:

Fixed the DHCP issues based on the official firmware 1.2.1 Build 20220512.

ER7206(UN)_v1_1.2.3_Build 20230118 (Beta)

Beta Release Note:

Fixed the DHCP issues based on the official firmware 1.2.3 Build 20221104.

Notes:

(1) Please be sure you have read the Beta Test Agreement before proceeding!

(2) The above Beta has added the fix for the DHCP Reservation issue mentioned HERE.

For ER605 V2 and ER8411 V1, please check for the official firmware below to fix the DHCP issue.

ER605 V2_2.1.1 Official Firmware (Released on Jan 30th, 2023)

Note: the firmware is applied to ER605 V2 and V2.60.

ER8411 V1_1.0.2 Official Firmware (Released on Jan 30th, 2023)

Note: the firmware is applied to ER8411 V1 and V1.60

Thank you all for your great patience when we're trying to figure out the issue and fix it!

Any further issues with the above Beta firmware, please feel free to comment below or Start a New Thread from HERE.

Updated on Nov 11th 2022:

The official firmware ER7206_v1_1.2.3 has been released to fix the DHCP issue.

**The above ER7206 1.2.3 firmware is available in the cloud, fully adapted to Omada Controller v5.6. 

Updated on Nov 2nd 2022:

Update the Beta firmware to fix all the DHCP issues that have been reported to the support team, including the issue

• DHCP Server failed to assign valid IP addresses to some clients. Reported Here.
• Different clients have duplicated IP address on the Omada Controller. Reported Here.
• Offline wireless clients were still shown up in Clients list and reported as connected to the Omada Router. Reported Here.

ER605(UN)_v1_1.2.2_Build 20221015 (Beta)

ER7206(UN)_v1_1.2.2_Build 20221025 (Beta)

ER605(UN)_v2_2.0.2_Build 20221025 (Beta)

*The above beta firmware is adapted to Omada Controller v5.5, not for Controller v5.6.

Note: 

ER605 v2 ONLY have the last DHCP issue mentioned above, which is a mis-report by the router.

Updated on Sep 21st 2022:

Remove the 0918 Beta firmware as some users reported it causes CPU spikes issue.

Updated on Sep 19th 2022:

Update the Beta firmware and add the latest Beta firmware for ER605 v2/ v2.6,  which have added the fix that Omada Router may wrongly report the clients status to the Omada Controller, causing the issue that offline clients were still shown up in the Controller Clients list, and connected to the Omada Router (instead of the SSID or network). For more details, check this related post.

ER605(UN)_v1_1.2.2_Build 20220902 (Beta)

ER7206(UN)_v1_1.2.2_Build 20220902 (Beta)

Newer version >> ER605(UN)_v1_1.2.2_Build 20220918 (Beta)

Newer version >> ER7206(UN)_v1_1.2.2_Build 20220918 (Beta)

Newer version >> ER605(UN)_v2_2.0.2_Build 20220918 (Beta)

This Article Applies to:

ER605_v1/ v1.6

with FW 1.2.0 Build 20220114 or FW 1.2.1 Build 20220512

ER7206_v1/ v1.6

with FW 1.2.0 Build 20220117 or FW 1.2.1 Build 20220512

Issue Description/Phenomenon:

Recently we received feedback that the DHCP Server failed with 1.2.0 and 1.2.1 firmware, the issue may manifest as follows:

• DHCP Server won't provide dynamic IP addresses to end clients in some cases.

     Related Post: DHCP Server Fails Every Few Hours

     (1) simply clicking Save on the Edit Network page will bring the DHCP server to work for a few hours.

     (2) reboot doesn't help, the issue doesn't exist with the router firmware 1.1.1.

• Some clients are assigned the same IP address, causing they cannot access the internet.

     Related Post: Issues with DHCP, clients get same iP addresses

     (1) rebooting the router will solve the issue for a while.

     (2) the issue doesn't exist with the router firmware 1.1.1.

Note: 

ER605 v2 doesn't have the two DHCP issue described above.

Thank you all @jdpk, @Karel-24, @PascalSBR for reporting the issue with detailed information, and your great cooperation with our support engineers to look into the issue is much appreciated! 

After further investigation and tests, the TP-Link team has addressed the problem finally.

Available Solutions:

Update as of Apr 17th 2023: 

The following official firmware has fixed the DHCP issue mentioned in this thread.

ER605 V2_2.1.2 Official Firmware (Released on Feb 14th, 2023)

Note: the firmware is applied to ER605 V2 and V2.60.

ER7206 V1_1.3.0 Official Firmware (Released on Mar 28th, 2023)

Note: the firmware is applied to ER7206 V1 and V1.60.

ER8411 V1_1.0.3 Official Firmware (Released on Mar 17th, 2023)

Note: the firmware is applied to ER8411 V1 and V1.60.

ER7212PC V1_1.0.3 Official Firmware (Released on Mar 21st, 2023)

For ER605 V1, you may install the Beta firmware below to fix the issue temporarily.

Beta Firmware Download:

ER605 V1_1.2.3_Build 20230413 Beta Firmware For Trial (Released on Apr 14th, 2023)

Notes:

(1) Please be sure you have read the Beta Test Agreement before proceeding!

(2) The above Beta has added the fix for the DHCP Reservation issue mentioned HERE.

Update as of May 22nd 2023: 

The following official firmware has fixed the DHCP issue mentioned in this thread.

ER605 V1_1.3.0 Official Firmware (Released on May 17th, 2023)

Note: the firmware is applied to ER605 V1 and V1.60.

As the official firmware has been released to fix the issue, this thread will be locked to stop updating.

Any further issues or concerns, please feel free to Start a New Thread from HERE.

To get better assistance, you may check Tips For Efficiently Reporting an Issue In The Community.

Thank you all for your great patience when we're trying to figure out the issue and fix it!

Previous Solution Post:

ER605 ER7206 - “Use Fixed IP Address” (DHCP Reservation) Doesn't Take Effect