IPSec suddenly stopped functioning properly

[bbiketa]

Hello,
I have one Pfsense running vpn tunnel with one user's Sonicwall firewall for almost 2 years without breaking or problems. Both locations are on fixed public IP. Today it suddenly stopped functioning properly, no changes were made to any side at all. In status the PFsense says vpn is running, but no traffic is going through. Interesting is that when you press + to expand child entries, pfs registers in and out traffic (very low amount) that's going between connected networks which are in Phase2. After I renigotiate/restart tunnel it starts working normally again. Logs on both sides says everything is fine, it makes normal negotiation, both Phase1 and Phase2.