Not sure but I would suspect some type of electrical interference such as something that is turned on during that time. As a test, try moving the powerline adapter to a different plug maybe the same one as the router is plugged into.

@Phillipj 

 

@ArcherC8 is right in that there is something being introduced into the wiring that is causing interference. Especially if it happens in a pattern. If anything try and note what happens around that time.

It's really eratic. Just now we got 3mbps and within seconds none at all. 5 minutes later everything just the same went off again.

If we never had it working i would just think it didn't work.

So frustrating. 

I do not have a powerline adapter but do have X10 controls for some exterior lights. X10 controls use the power line to transmit signals between the controller and the controls and I had to add a phase coupler as some of the lights were on the other electrical phase from the X10 controller. (220 is made up of two 110 volt phases. 110 volt devices uses only one side of the two phases). Without it it was hit or miss if it would work. After I added it, They work fine. Not sure if the power line adapter has the same type of issue or not. That is why I suggested doing a test by plugging the powerline into the same circuit. If it okay on the same circuit, I would try a phase coupler as they are only $1.00 or so on ebay. Maybe TP Link has a product for that. Let us know what happens.

@ArcherC8 

Thank you for your recent replys.

I have now found the problem.

When i put on the lights in my holiday cottage this is when i either lose the wifi conection or its simply so slow its unusable. 

Have you ever come across this problem and if so what was the remedy. 

Fingers crossed you can help.

 

Sounds like something is causing an electrical interference. I assume there is a electrical panel for the cottage. I would start with all the breakers off and turn them on one at a time until you find the one causing the issue. Then start checking all of the items on that circuit by unplugging them. If you can not unplug, turn them off. If all the items on the circuit are unplugged or off and still have an issue, then you may have an electrical problem. Dimmers and fans can often be a cause.