EDIT: So did I! Read below anyway.
Unfortunately, with all the modern security issues, Windows 10 updates often not working properly or breaking things, and networking just getting more complex, we all need to learn enough to be able to fix stuff these days. You'll manage.
I downloaded the manual for your router from here;
https://www.netgear.com/support/product/r6250.aspx#docs as it looks like you are in America. (I'm in Australia.)
What you need is on Page 36 of that manual, and is called "Address Reservation". The instructions there are pretty good. There is some explanation on Page 35 that is worth a read.
I recommend you do follow the advice to use the "Attached Devices" screen (Page 26) to view your connected devices, including the Windows 10 PC on wireless, and copy the MAC Address from there, to avoid any possible errors typing. You will also be able to confirm the IP Address that the Windows 10 MC PC is using now. It is easiest to use the same IP Address in the reservation.
Do make sure you reboot the Windows 10 PC after making the above change. It wouldn't hurt to completely power down your Yamaha 3060 as well, and then restart it.
This may not fix your original issue with the Windows 10 MC Server dropping off the network, but it is a good start. If the problem persists it could be there is some form of interference, even just a warm, wet human body walking up stairs between the router and the PC can cause issues if the signal is a bit dodgy. But you say the signal is strong, so we shall see.