@zageng 

Ok, so when using WDS on the TL-WR841ND v7, then you get no connection to the Huawei Echolife, no matter if it's nearby of far away. Is that correct?

Well, if you are not afraid of potentially bricking your TL-WR841ND v7, then you could try your luck with DD-WRT. In DD-WRT a regular range extender mode is available. (it's called "Station Bridge" in newer versions of DD-WRT)

But keep in mind that DD-WRT offers no assisting features like "Quick Setup" or "SmartDHCP". In DD-WRT all settings have to be configured manually.

And there might not be a way to revert back to the TP-Link software later on.

  @woozle is it compatible with my tplink wireless router, It doesn't matter i don't want to revert back but will it fix the problem

as for the echolife no it is not related to the type of router, i try to connect to a tplink 9960 it don't work eithter 

  @zageng 

DD-WRT is available for the TL-WR841ND v7. Make sure you download the correct version. (tl-wr841ndv7)

I usually install a version that is about two or three weeks old, thinking that if a version turned out to have a major flaw it would have been pulled from the server by then.

Note that nobody can guarantee whether DD-WRT would fix the connection problem or not.