@Wrayman Thank you very much for your answer.

Start IP is 192.168.68.50.

End IP is 192.168.71.250

Si I guess it's ok.

In fact, my devices that cannot connect to "Garage congel" do connect finely on other nodes without any problem.

  @Symph 

Do you actually need such a large range of IP addresses?

I have observed some anomalies when setting the LAN IP Subnet Mask to something else than 255.255.255.0.

I suggest setting the DHCP range to [192.168.68.50,192.168.68.250], and setting the LAN IP Subnet Mask to 255.255.255.0.

  @yves_b Thank you very much.

I restricted the range as you suggested and corrected the LAN IP Submask.

It unfortunately didn't work :(

  @Symph 

Could be hardware issue with "Garage congel".

Try the following:

1. Delete "Garage congel" from Deco mesh, which will also reset that Deco unit. Follow Reset a Deco unit from How Do I Reboot or Reset My System?

2. Power off "Garage congel" X75 and put is aside, together with its power cord.

3. Bring "Cuisine" with its power cord to where "Garage congel" was, configure it to connect to Main Deco (if you have to) and rename to "Garage congel".

Check if new "Garage congel" does accept new clients and Deco mesh is stable.

If it does, your old "Garage congel" has some hardware/firmware defect, most likely.

If you want to, take that Deco unit which you reset, add back to Deco mesh, configure as "Cuisine". On a slim chance resetting it fixed whatever issue there was.

  @Alexandre. Thabks for your answer.

I also believe it's hardware problem.

I will try to habe it replaced since I bought that product in July.

I hope TP-link will habe it replaced at no cost but don't believe it that much.

thanks again

yves_b wrote

  @Symph 

Do you actually need such a large range of IP addresses?

I have observed some anomalies when setting the LAN IP Subnet Mask to something else than 255.255.255.0.

 

I suggest setting the DHCP range to [192.168.68.50,192.168.68.250], and setting the LAN IP Subnet Mask to 255.255.255.0.

  @yves_b you know the 22 bit subnet mask is the default on the XE75?

When I was using the XE75 I thought that might have been a problem but it turned out my problems were due to some application setting assuming a 24 bit subnet mask.

However I do agree it's worth a try I doubt it's the source of the problem.

I wonder if it's the mismatching firmware versions?

On my regional tp link web site firmware 1.2.1 Build 20230601 Rel. 58453 is for XE75 V2 (there is no corresponding firmware for V1), while Deco XE75(US)_V1_1.2.8 Build 20230901 is for XE75 V1 (there is no corresponding firmware for V2).

It's worth checking IMHO.