So, all 3 routers do have wifi on and allow clients to connect. The two cpe510 antennas make a ptp link and they work fine, signal strenght is around 50% and they dont lose connection. My isp router has ip 192.168.0.1. and dhcp on in range of 192.168.0.20 to 192.168.0.100 and it is working fine and clients can connect to it. The two cpe510 antennas have ip's 192.168.0.3 and 192.168.0.4 and on both dhcp is off and their signal and connections are ok. the router connected by wire to the cpe510 receiving the signal is connected to Lan port and has ip 192.168.0.2. and dhcp is on from 192.168.0.120 to 192.168.0.250 and it works fine. The last router sometimes allows clients to connect and sometimes not, it is working as a repeater and has its ip 192.168.0.254 and dhcp off.
What settings should I change?
You have two DHCP servers on the same network. That is bad.
The first router that is wired to the second CPE510, set it to access point mode. You can use the same 192.168.0.2 management IP. You can leave the cable in the LAN port, that's fine.
The CPE510s are set up as just AP/Client mode right (one is AP, one is client)? Not router mode?
The repeater should be fine as-is.
Might be easier if you change your diagram to show the MODE of each device. A router acting as repeater is just a repeater.
Also make sure the CPE510s are set with their own unique SSID and use it only for that P2P link, don't connect any clients to them. Best to let them just do their job and not try to handle clients too (unless you have a specific need for them to). You can even hide the SSID for simplicity, but not required.
The alternative is to move the cable on that router to the WAN port, and set the LAN to some other subnet, like 192.168.1.x. You will be in a double NAT setup, which is not necessarily a bad thing, it actually helps segment your network off and prevents unnecessary broadcasts from going all over the place. However if you need inbound access from the internet you'll need to configure it on both the ISP router and your second router, just something to keep in mind. But if you don't have a ton of devices, the AP mode option above should be fine and easiest to manage.