Flies vpn routing through Yota, give me some ideas?

Question

linux

Linux --> ZyXEL --> Yota --> Internet
I connect on nix'e with ppptp the server of office, the ppp0 interface rises, the address internal static is assigned, the route rises. everything is fine
, usually when accessing the internal address of the office network, this route suddenly flies (not always).
I raise it with my hands through watch -n3 script_name
the "script" itself in one line:

#!/bin/bash
 && route add -net 192.168.50.0 netmask 255.255.255.0 gw 192.168.50.225 dev ppp0 && echo "reUP!"

it seems you can live, and yet it is not convenient, because in some places everything freezes with the loss of the route, the rise takes 5-7 seconds.
I sin on the ZyXEL router, because with the yota modem plugged into the computer, the routes do not fly off. Any ideas why this is happening? The router shits (crossed out) pushes the table? To register on it a route static? Remove DHCP? Connect via vpn on the router and not on the client? Throw ideas)

Answer 1

Directly, a router cannot change the routing table on your host.
Perhaps the DHCP lease sours, the host re-requests the lease of the address, while the host itself may change routes. Try setting a static IP on the host.
If so, then it is not the router that is to blame, but the specific implementation of the IP stack on Linux.