Here some information that might help some people. I have been using MySensors for many years now, and often struggled with some connectivity issues: Mostly due to concrete, and I also think due to the P1 port updates take a moment to upload online (even with a custom gateway which keeps the HTTP connection open, etc.)
Recently my "old" NodeMCU gateway just failed, apparently a bit too much pressure on the USB cable and after 1.5 years of service in a new spot, it just broke the connector (obviously during a long weekend away )
As it was the last one of that type (LoLin NodeMCU 1.0), I decided to use some other equipment. Also, I wanted to make a simple "MySensors doctor" which just sends packets and gets something back - so much less functionality than the version described here: https://forum.mysensors.org/topic/9178/nrf24doctor
So while testing the new gateway, I also noticed that my ESP8266 Wemos/NodeMCU repeater was just behaving poorly. Tried various power supplies and multiple NRF24 modules.
After reading mixed opinions about powering through USB and the 3v3 pins of the NodeMCU, I decided just to try and build a very simple separate "power supply" using the following parts:
USB to DIP connector (https://www.google.com/search?q=usb+to+dip&client=firefox-b-d&source=lnms&tbm=isch these with 4 pins)
a big capacitor (my one is 670uF?) and smaller capacitor (10 uF)
a 3.3v step down module (something which can handle 5v and bring it to 3.3v). I used: https://www.aliexpress.com/item/1005002610674227.html?spm=a2g0o.order_list.0.0.21ef1802d20uHi
I put these together as shown in the image in an very experimental setup... and now power the radio module from the 3v3 from the regulator, and the ESP8266 from the "stabilized" 5v supply (through the vIn pin). The change in performance has been absolutely phenomenal. Nodes Instantly connect to the repeater (quite some concrete away) and also my "mySensors doctor" suddenly reports way better connectoins: a lot of the radio modules which I considered non functional (fakes) seem to work instantly. No additional PAR requests - just instantly!
Now, sample size is just one here.. but for me this conversion really paid of and now also considering to make similar adaptions to the gateway (which is now a ESP32, experimenting with double threading for P1 from electricity meter and gateway separate, to have less interference from the P1 every second... already wrote that code, just need to connect again some wires at the power meter.) - and more important: running on the USB port of the firewall .
Hope it's not too much rambling. For me it really paid of, and has been such a simple yet great improvement that I would recommend others that have issues to try it too.