See issue #750. zerotier doesn't currently set a metric on routes. Linux takes this to mean "0", the highest priority. Every comment in the issue is about routing between zerotier and lan and how they conflict. This quick change could fix this problem for most people. The subnet route for the zerotier network, the one with no via, is still 0 in this patch. Just the "via" routes get higher metrics. If for some reason, you needed your via routes to have higher priority, you could use a prefix work-around: 192.168.1.0/25 via 10.147.17.1 192.168.1.128/25 via 10.147.17.1
OS-Dependent and OS-Interface Things
This folder contains stuff that interfaces with the base operating system like Phy for network access and the various OS-specific Ethernet tap drivers.