My system consists of JRiver MC 29.0.22 64 bits installed on a PC with Windows 10, two DLNA renderers created by BubbleUPNP from two Chromecast Audio devices. BubbleUPNP is installed on the same PC. Music files stored on attached USB SSD. Windows Defender has been treated following the recommendations. No other antivirus is present on the system.
My system is very similar, running for a couple of years with two original Chromecast Audio (CA) dongles, visible to MC as DLNA renderers through BubbleUPnP Server. I have certainly worked through a challenging range of connection issues. Reboot needed - yes many times to clear network issues while debugging - but in the last few months it is rare for MC itself to crash. I use McAfee Total Protection, "not" Windows Defender. I use a WLAN app to remotely wake up the server from sleep if necessary and then start playing from Android.
The DLNA renderer can be disconnected and reconnected either within MC (by unchecking and rechecking the advanced option 'DLNA Controller (control other DLNA devices), or through BubbleUPNP, by unchecking and rechecking 'Create a DLNA renderer'.
The crash occurs only if the DLNA renderer has been previously used by JRiver since restart. If only the local zone has been used since restart then no crash occurs.
I tried both of your disconnect/reconnect tests tonight, and neither crashed MC. After reconnect I just started MC playing to the CA again without problem.
A smorgasbord of tips that work for me:
1) In MC server, set
Options > Startup > Windows Startup > Run on Windows startup: Media Center and Media Server. In Windows Services, check that both
BubbleUPnP Server and
JRiver Media Center Service 29 are set for
Startup Type: Automatic. Together, these will leave Bubble, MC Server, and MC running after a reboot, even without logging in to your desktop.
2) Very important to use latest version of BubbleUPnP Server (0.9-update42 or greater).
3) Be sure the PC server is using the 2.4GHz Wi-Fi band. While a dual band Wi-Fi router can sometimes play to the CAs on the 5GHz band, I find CAs can only be discovered on the 2.4GHz band with my NETGEAR router.
4) At least for testing, and a good idea in general, be sure there is only one MC Server on your network. While multiple MC client PCs are fine, I do not set them up as servers, just to avoid any possible confusion.
5) In Win11 Network & Internet Settings, my home network is "Private", with its Network Discovery & File/Printer Sharing all turned on. On another networked computer, my server PC appears under Windows Network > "Computer" (as well as under "Media Devices" and "Other Devices").
6) Lately any time I have a CA connection issue it is traceable to BubbleUPnP Server, never MC. When BubbleUPnP is healthy (showing your MC Server, and CA Renderers as DLNA devices, as you describe), then all my Android apps are functional (MO 4Media, MC Panel, JRemote2, BubbleUPnP app). If BubbleUPnP Server is not ok, then the Android apps all fail, except possibly BubbleUPnP app which might play directly through its local server (I think you saw the latter).
7) Be sure all firewall exceptions for Local TCP/IP Ports and Local UDP Ports are set up for MediaCenter29, BubbleUPnPServer, and Chromecast.
8 ) Set up Wi-Fi router to use static IP addresses.
9) On rare occasions, after significant network changes, it is necessary to power-cycle the Wi-Fi router as well as reboot the server PC.
10) In the MC server PC > MC left panel tree, check
Services & Plug-ins > Media Network. It should report that all 5 servers are running properly.
11) Use Whitebear DMRA to confirm normal operation of CA renderers.
12) As a test, set the MC server PC to never sleep (Windows power settings) and see if that eliminates your overnight "disconnect" issue.
13) If using Android apps to control MC Server over Wi-Fi, be sure phone is set to
auto-reconnect to your LAN's 2.4GHz network. Without
auto-reconnect, phone app connection to MC is very sketchy, even when phone appears on router's attached devices list and otherwise functions normally. On Samsung Galaxy S9 (Android Ver. 10, One UI ver. 2.5):
Settings > Connections > Wi-Fi > Current Network > Settings > Auto-reconnect. (item added 7/8/2022)Hope this helps. I've thought about replacing CAs with Ras Pi many times, but so far have not jumped ship.
MC 29.0.22 Windows 11 Pro 64-bit