When your rate of PL-751 is low, please refer to the following steps to improve the quality.
1. Please check whether your Powerline adapters are separate by power outlet. If yes, please move the adapter on the outlet to the wall.
2. Please check whether there is electrical equipment which has electromotor inside around the Powerline adapters. Such equipment can be air-conditioner, washing-machine, electric fans, etc. Please move such equipment to other places or move Powerline adapters away from such equipment. What is more, you can buy a power outlet which has surge protector function and plug such equipment to the outlet to avoid interference.
3. Please check whether there is AC power adapter that is used for mobile phone, laptop or something else around the adapter. If the quality of AC power adapter is not good, it may make great noise to the power line circuit. Please move it to the other and move it far away from the Powerline adapters.
4. Please check whether the distance between the adapters is long enough. In theory, the longest distance is 300 meters. However, with the interference and line quality, it’s hard to reach 300 meters.