I have added this in OpenWRT → Routing
Interface: wgserver
Route tye: unicast
Target: 10.10.10.0/24
Gateway: (ignore)

It is shown on routing table:

root@GL-AX1800:~# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         0.0.0.0         128.0.0.0       U     0      0        0 wgclient
0.0.0.0         xxx.xx.xxx.1    0.0.0.0         UG    0      0        0 eth0
10.10.10.0      0.0.0.0         255.255.255.0   U     0      0        0 wgserver
128.0.0.0       0.0.0.0         128.0.0.0       U     0      0        0 wgclient
xxx.xxx.xxx.1   xxx.xx.xxx.1    255.255.255.255 UGH   0      0        0 eth0
192.168.0.0     0.0.0.0         255.255.255.0   U     0      0        0 br-guest
192.168.50.0    0.0.0.0         255.255.255.0   U     0      0        0 br-lan
xxx.xx.xxx.0    0.0.0.0         255.255.255.0   U     0      0        0 eth0

But I cannot connect to 10.10.10.2.