Then only use that relay if it works with 3.3V on VCC. Powering that from 5V is sinking that to your D1mini Gpio, and D1mini doesn't like it.
So you turn relay on writing gpio low and turn it off writing gpio high.
That type of relay module that requires a low to turn on the relay uses a pnp transistor to switch the relay.
When the module is powered by 5V, the 3.3V output of the Wemos D1 mini is at -1.7V with respect to the emitter of the pnp transistor.
This is likely to be enough to either turn on, or prevent the turning off of the relay.
That means that there's voltage coming back through the IN pin? I measured that when I was using the HW-553.
So can I power the relay with 3.3 from wemos? It should be just 100mA
On the border line.. If it works ok at 3.3V and D1mini voltage regulator doesn't get too hot, your'e fine
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I've never used one. Would the PNP 2N3906 TO-92 work?
it's more quiet when powered with 3.3V
No need to.
I was saying that the module itself has a pnp transistor on the PCB.
And using that to explain why things don't work correctly when you power the module from 5V, but have a 3.3V input signal.
Oh, I misread, sorry 
Coil is energized with 3.3V instead of nominal 5V.
Probably with 3V it wouldn't even work.
So I could have reliability issues, I suppose
When you operate stuff out of their specs, you always have that odd.
That relay is designed to be operated by 5V MCU, like Arduino uno.
If it is a LOW level trigger, then this simple circuit will work
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Thanks so much!
You are welcome!
Hi, @mmtyy
Can you post some images of your project?
So we can see your component layout.
Thanks.. Tom.... 
