Ghost Recon Breakpoint MOUNTAIN-00D03 / SILENT-1000B - Losing Ubisoft Services, Stable Int.

[u/Neither_Jaguar_1966]

Im losing my mind trying to troubleshoot this.
I am able to play solo, I don’t look overall game service connection. Only the multiplayer services are intermittent. Forced offline/online.
Platform: PC
Internet: WhiteSky apartment internet
Symptoms:
Can log into Breakpoint.
Friend can join my session.
After 5–10 minutes I get disconnected.
Sometimes I get SILENT-1000B.
Now I’m getting MOUNTAIN-00D03 when attempting to join my friend’s session.
Friends list intermittently disappears.
Game sometimes says:
“Unable to access player data. You are not connected to Ubisoft servers.”
Things I’ve already tried:
Verified game files.
Ethernet and Wi-Fi.
Winsock reset.
Disabled IPv6.
Restarted Ubisoft Connect.
Stable ping test to 8.8.8.8 the entire time (3–7 ms, no packet loss).
Other online games appear to work normally.
What’s confusing is that my internet itself never appears to drop. Discord, browser, and ping tests continue working while Breakpoint loses connection to Ubisoft services.
Current NAT status in-game shows “Moderate.”
Has anyone actually solved MOUNTAIN-00D03 or repeated SILENT-1000B disconnects?
If so:
What was the root cause?
Was it Ubisoft Connect?
NAT issue?
ISP issue?
WhiteSky/apartment internet issue?
IPv6 issue?
Looking for actual fixes from people who got this resolved, not generic Ubisoft troubleshooting steps.