Gx450 upgrade firmware from 4.8 to 4.9, now can't access devices behind modem via VPN

I upgraded GX450 modem from 4.8 to 4.9, now I can’t access any devices connected to the modem via VPN. If I downgrade to 4.8, I can access again. I can ping modem’s ethernet IP address via VPN which is 192.168.13.31. It seems the modem is not passing through the traffic. Anyone else having this problem?

I turned on the debug log for security and this is what I think that’s suspicious:
ALEOS_SECURITY: VPN Tunnel is down - Insert DROP rule in FORWARD filter for 192.168.1.1/24

That log just tells me the modem somehow sees the VPN tunnel is down and drops all traffic from my network 192.168.1.1? The VPN tunnel is up for sure as I can ping modem’s ethernet IP via VPN.

BTW, same issue happens to the RV50s I have.