How to access client behind site connected to OVPN/OPNSense from other client?

[errellion]

Hello forum,

I'm in the process of migrating from my NetBSD router with PF and OpenVPN server to OPNSense. Everything went smooth with some tweaks here and there. I have sucessfully imported my certficates and recreated config in OpenVPN Instance and also ccd/ settings, and basically all things are working but one thing. Here is a setup and I will explain my problem after that:

OpnSense address: 10.1.78.1
OpenVPN address: 10.66.77.1
Site A network: 10.1.78.0/24
Site B network: 10.2.78.0/24
Site C network: 10.3.78.0/24
VPN network 10.66.77.0/24

There are clients in network A, B, C.
All traffic is possible between clients in: A-B, A-C, B-A, B-C, C-A, C-B.

Only thing that isn't working (and was working in original config) is that when I connect with my phone. Phone is getting address ex 10.66.77.5 and I can easly access anything in network A, ex 10.1.78.5.

However accessing anything in Site B or C is impossible.

I tried looking in logs in GUI - no traffic logged from 10.66.77.5 when reaching anything from B or C.
Tried tcpdump on OPNsense itself on ovpns1 interface no traffc logged from 10.66.77 to ex. 10.3.78.6

Tried adding NAT on LAN and OpenVPN network.
For OenVPN interface there is a rule allow any:any

On router/client on lets say site C there is proper route for 10.66.77.0/24 network pushed from server (as well as routes to site A and B which traffic works in any direction)

u-SYS-fw01$ route show
Routing tables

Internet:
Destination        Gateway            Flags    Refs      Use    Mtu Interface
default            10.208.166.1       UGS         -        -      -  xennet0
10.1.78/24         10.66.77.1         UGS         -        -      -  tun0
10.2.78/24         10.66.77.1         UGS         -        -      -  tun0
10.3.78/24         link#2             UC          -        -      -  xennet1
10.3.78.254        link#2             UHl         -        -      -  lo0
10.66.77/24        10.66.77.1         UGS         -        -      -  tun0
10.66.77.1         10.66.77.4         UH          -        -      -  tun0
10.66.77.4         tun0               UHl         -        -      -  lo0
10.208.166/24      link#1             UC          -        -      -  xennet0
10.208.166.10      link#1             UHl         -        -      -  lo0
127/8              localhost          UGRS        -        -  33624  lo0
localhost          lo0                UHl         -        -  33624  lo0

I'm out of ideas right now