This sounds reasonable. Curiously now that I tried again with both host lan & wlan active there was no problem. I have a hunch the routing depends on which interface networkmanger starts first.
$route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
default 192.168.102.1 0.0.0.0 UG 600 0 0 wlp19s0f4u1u1
default RT-AC86U-6D60 0.0.0.0 UG 20100 0 0 enp15s0
192.168.2.0 0.0.0.0 255.255.255.0 U 100 0 0 enp15s0
192.168.100.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr1
192.168.102.0 0.0.0.0 255.255.255.0 U 600 0 0 wlp19s0f4u1u1
192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0_
When the host routing table is like this:
the VM has internet connection. If the defaults are the other way around it doesn't.