@olivierlambert I'm not sure, but that seems to be the case. It does eventually reconnect, but XO-6 is unusable over the SD-WAN whereas XO-5 runs flawlessly. I'm happy to do more troubleshooting if that would help or if there is interest in pursing further. I'm sure this is not a common use case.

Here is the actual message from the browser console:

Close the SSE connection due to an error 
error { target: EventSource, isTrusted: true, srcElement: EventSource, eventPhase: 0, bubbles: false, cancelable: false, returnValue: true, defaultPrevented: false, composed: false, timeStamp: 159239, … }
watch-collection.composable-gsPsDzPK.js:1:1267
    f http://10.0.1.20/assets/watch-collection.composable-gsPsDzPK.js:1
    Wn http://10.0.1.20/assets/_plugin-vue_export-helper-Dc4GNrzR.js:1
    B http://10.0.1.20/assets/_plugin-vue_export-helper-Dc4GNrzR.js:1
    call http://10.0.1.20/assets/_plugin-vue_export-helper-Dc4GNrzR.js:1
    C http://10.0.1.20/assets/_plugin-vue_export-helper-Dc4GNrzR.js:1
    Wn http://10.0.1.20/assets/_plugin-vue_export-helper-Dc4GNrzR.js:1
    sr http://10.0.1.20/assets/_plugin-vue_export-helper-Dc4GNrzR.js:1
Uncaught (in promise) TypeError: NetworkError when attempting to fetch resource.
    w http://10.0.1.20/assets/define-remote-resource-D2cyqlxv.js:2
    AsyncFunctionThrow self-hosted:785

I have two sites in the SD-WAN (created over two UDM-pro's). XO-5 works well, and has for months. When I upgraded to XO-6, I started having server connection issues. It doesn't appear to be the 30s issue that was patched in April, as I will physically lose connection (pages won't load). I did some research, and fed the issue into Claude, and it seems to point to an architecture change between the keep-alive format (SSE in V6, vs Websockets in V5).

Does this make sense? Has anyone encountered this before? Thoughts/suggestions? I can stay on V5 with no issue, but was hoping to learn V6 more.

Thanks!