A lot of node-RED users are using ESP devices to provide environmental or other data for node-RED to process, so this post is vaguely on-topic
I've just replaced my router, which although has more features, is lacking in wifi power (Netgear Nighthawk), and has resulted in dodgy MQTT communications between an ESP in my greenhouse, which is about 20mts distance from the router, including 2 brick walls.
As can be seen in the image below, the s/s up to about 13:00hrs was in the region of 76db before dropping out completely at 80db.
I tried a few few different options up until 13:30hrs, before adding a ground plane to the ESP.
The ground plane was nothing more than a metal oven tray, similar to this, which was placed beneath the ESP enclosure. Not grounded, just placed down, and the ESP enclosure resting on top.
As can be seen, the s/s improved by 10db, which is the difference between a good solid signal, and no signal at all....