For occasional "special" gigs (i.e. where we get paid more than normal) we bought a dozen or two cowbells like this on Amazon and passed them out to the crowd immediately before we play "Honky Tonk Women". The bells are $1 each and barely last the song, which is perfect.
Audience reaction has been great, but we also wait until everyone's liquored up. Also, our drummer's own cowbell is miked, so we can turn his up to avoid the inevitable poor timing that the crowd introduces. We really play it up - have the audience "practice", really ham up the demonstration, etc.
Alternatively, we've done the same thing with just a single audience member - if it's their birthday, reason for the gig, etc.
Your experience and mine differ then running a 5.8ghz link between two buildings about a thousand feet apart in heavy (torrential) rain using directional POE wifi bridges such as this one https://smile.amazon.com/gp/product/B072Y5S8YX/
I use something similar on the family ranch to reach the shop buildings located about 1000 feet / 300 meters from where the Starlink is mounted at the house. I used these https://smile.amazon.com/gp/product/B072Y5S8YX/ they are limited to 100 mbps on the hardware ethernet port, so are a bit slower than Starlink on a fast day, which works ok for me.
I am doing something very similar using a TP-Link RE450 to convert from wifi to ethernet, then household WavLink Mesh, which feeds a wifi bridge to an outbuilding about a thousand feet away, using a pair of these https://smile.amazon.com/gp/product/B072Y5S8YX/ Works well except in heavy rain where I get dropout on the wireless link before starlink drops out.
I have a second house on my property where my Mom lives and I extended my internet and Dish network to her house using one of these: Wireless bridge
Not necessarily making a brand recommendation, but more of a concept recommendation. The instructions were not great on this one, sorta like they were written in another language then run through Google Translator. Got the job done but required some trial and error.
The 40 meters you describe is well within the max length of the cable (at least for CAT 5 & 6). The connector connecting the two segments together may be introducing loss. Try replacing that first then if it does not clear up, try another port on the switch end and/or a different Ethernet cable. If you can swing it go fully wireless with this or something similar: https://www.amazon.com/QW-CPE5450-Wireless-Bridge-Point/dp/B072Y5S8YX/
Wireless will need a clean line of sight.