RFM69 and Ethernet shield share SPI bus, each one with its own CS line. Ethernet shield uses pin 10 so JP1 should use pin 6 for the radio. Issues sharing SPI bus seems to be due to bad SEN line handling as described here. The official Arduino ethernet shield suffered from this, but most commonly used clones work ok. Shields including 74LVC14 as in the pic should work ok.

Hi, sorry for the delay, I had just read your post and I could said "me too" But I solved the problem and it works for two years now. I explain my solution here, if the French don't afraid you. https://easydomoticz.com/forum/viewtopic.php?f=20&t=6497 I resume, a 7.5volts power supply, a passive injector, and a spécial home-made cable to bypass the RJ45 socket. The 7.5 v go to Vin-Gnd of the Nano to produce 5v wich is returned to the W5100. QED. Rpx.