@rurencjusz 

Hi，thank you very much for the feedback. Based on the screenshots, actual address didn't add 100 compared with reserved address for all devices, for example, reserved address for 70:AF:24:11:82:7F is 192.168.0.7, actual address is 192.168.0.106.

Besides, there is a RE305 in the client list of the router, may I know the hardware and firmware version of the RE305? V3 or higher version of RE305 supports OneMesh, please check if the RE305 and Archer MR600 are in OneMesh network or not.

If the problem still happens with OneMesh network used, please also try to unplug the RE305, then connect all devices to the MR600 to see if address reservation still have the problem.

By the way, what is the DHCP address pool configured on your MR600? you could also try to make sure all the reserved IP address are within the DHCP address pool to see if problem still exists.

  @rurencjusz 

Hi, sorry for that the problem still exists, please send an email to support.forum@tp-link.com with the following information, our engineer will continue to follow up the issue:

1. what kind of devices are able to get reserved IP address? are they connected to the MR600 via WiFi or Ethernet cable?

2. what kind of devices are unable to get reserved IP address, and what are their model no.? are they connected to the MR600 via WiFi or Ethernet cable?

3. after configuring the address reservation and saving the settings, did you try to disconnect from MR600 first and reboot the client device, then reconnect it to regain IP address?

4. what is the operation mode of your MR600? 3G/4G Router mode or wireless router mode?