Driver and connection of two CPE510 devices

I have two CPE510 devices from Tiplink Company. The devices were working perfectly and the internet was fast. The problem happened before, which is that the internet becomes very weak even though the devices are connected together, the cable has been checked now and it is good, the problem I have is that the internet is very weak, not exceeding 1 Mega even though my service provider has 100 megabytes, I think the problem is from the IP, but I am not sure or how to identify it.