FYI, these are TWO different Serial connections 
One for the ESP
And the other for Serial Monitor diagnostics.
Dear friend
I have some project use same your part
Arduino nano + Esp 8266 (v1)
I my device working good
Arduino : ESP8266
Pin2 --> TX
Pin3 --> RX
Baudrate : 9600 (or 115200) for all
Default of ESP8266 is 115200 but i down to 9600 to avoid connect fail
You should try to do it
Dear
BTW, I pulled those quotes from earlier post… This OP has already adjusted the speed, loaded the new firmware and resolved the issue
1 Like
@lemanh_1988 have you ever tried using something like a Wemos D1 Mini?
I use them for virtually all my projects, despite having quite a few Arduino Uno’s and Mega’s and ESP-01s available to me.
There are very few modern sensors that aren’t 3.3v compatible, and where you have devices that can only work on 5v logic levels it’s very easy to use a level shifter. The only device I’ve had this problem with was an RFID reader and a level shifter fixed the issue in a couple of minutes.
The great thing is that there is a massive choice of devices and connection methods out there and people can choose the most appropriate device/method for their needs. I’d just prefer it it people opened their eyes and their minds to something other than an Arduino and an ESP-01.
Pete.
Dear Mr Pete
Thank for your information but i have one question for you?
With wemos, how many analog input pin you can use ?
Arduino have : A0 ~ A7 for received analog signal input.
With wemos, only 1 pin. And if you want extend the number of connecting pins to adc pin
You need one more thing to extend : example IC4051 (it is difficult for everyone if they need learning more about arduino).
With arduino + ESP01 : i do not need modify the hardware
What do you think about it ?
Manh
Hi Gunner
Congratulation
Gunner is arsenal FC or what is your maining?
What, for being so wonderful??.. gosh thanks 
“Gunner” is just a long term callsign… paintball, video games, I even answered to that in a job where there was another person with same first name, but he was there first. I have been told it matches my personality 
That’s very true.
In practice though, very few modern everyday projects use analogue signals, and for those projects that do use multiple analogue sensors it’s usually quite rare that those sensors are located in exactly the same physical place.
Obviously running analogue signals from remote locations to one central point where your MCU is located won’t work, as the voltage drops and interference picked-up along the way will make the results unusable.
If you were in the position where you did need to work with multiple analogue signals for one MCU then it’s very simple to add something like this:
https://www.ebay.co.uk/itm/74HC4051-8-Channel-Mux-Analog-Multiplexer-Demultiplexer-Module-for-Raspberry-Pi/273535405127?hash=item3faffb0c47:g:pIEAAOSwmNlb2YN-:rk:1:pf:0
However, the original poster (and it’s his topic after all) is only using one sensor which is a digital device, so he has no need for any analogue inputs.
Pete.
Dear Mr PeteKnight
I understood about your explanation.
Although He only uses one sensor DHT11
However, what I want to say is : if someone wants to extend the application with more than one sensor (analog type). It is difficult if you have to use wemos. At that time, it will take at least 3 digital pins to control HC4051. It make output pin in limit
While we pay more money for the HC4051.
With only 4 dollars, I was able to complete my project without much difficulty, wiring easier than wemos.
Of course I don’t object to your way of doing it, but I think it’s quite easy to do because it runs on the arduino programmer’s platform
Thank you
Manh