@RuiV 

It is better to configure Client mode on the 2nd AP.

What do you mean when you say "it looks like the DHCP server kinda breaks and I can't get IP on any router." Do you try to connect some router to your 2nd CPE?

You are talking here only about 2 CPE, while you mentioned 3 of them.

CPE510 has directional antenna, so repeater mode is useless, so you will not be able to properly expand your wifi coverage. These devices are used not for expanding wifi coverage, but for transmitting signal by wifi on long distance. It is P2P, rarely Point-to-Multipoint, but not some Base Station for clients.

@Mitya 

Hi, thanks for response.

I say that the DHCP server breaks because once I connect the second CPE to the switch, the first router (another model) and of course the second CPE, both emit wifi signal but I get the APIPA addresses, which will not happen if only one CPE and the other TPLINK are connected.

For clarification, I have three CPE, but only managed to get two "working".

The third one, I didn't even try to configue it since I can't even get two working 100%., but the plan is to have three CPE connected and emitting wifi signal (being a total of 4 wifi routers, 3 CPE, 1 another model)

Another thing that might be a problem is that the first wifi router that is not a CPE, has some private class A IPs and the CPE have the C Class IPs.

Hope I could clarify and express my intention a bit better, please don't be afraid to ask more information about the setup.

And again, thank you so much for the help.

@RuiV 

It doesn't matter much, what IP-addresses are on CPEs, if you use L2 Modes (Bridge, AP, Client) and you don't use AP Router or WISP. CPE's IP-address is only for its management, while DHCP should go without problem. Of course, it is better to make everything in one subnetwork, so if you configure A-class on Router, you still can manually configure A-class for CPE also. However, I repeat, it should not affect clients somehow. I would try to configure static IP on the client of 2nd CPE. Also I would check SNR between two CPEs, so it is good (at least more than 20db). Just in case you can check and change IPs on both CPEs, so it is different and it belongs to subnet of the router. 

@Mitya 

Alright, I will try to get everything working with that modes.

If problems arrive, I will configure the CPEs on the same class as the other router.

Hope this finally works, thanks once again.

@R1D2 

Well, that indeed might be the problem maker of all this...

And very helpfull to know that the CPEs are class-less, helps on the fixing this.

Thanks a lot.