[strongSwan] auto=route makes local iOS DHCP fail

[Zesen Qian]

Hello list,
I set auto=route in a site-to-site tunnel, to keep the tunnel alive,
which makes an iOS in local net cannot get IP via DHCP.
ipsec.conf: https://bpaste.net/show/218b4db1df8b

0.DHCP client on PC(dhclient) works fine.
1.I can close the tunnel temporarily to let iOS get IP, and then
re-establish the tunnel, and everything works ok.
2.I can set auto=start, then everythng is ok. iOS can get IP even when
the tunnel is up.
3.The version is 5.2.2, I was told by my friend suffered by the same
issue that 5.2.1 works fine, though I 've not tried yet.
4.The DHCP server I use is dnsmasq, some logs on server when iOS trying
to get IP:
Mar  7 12:18:36 Riaqn-Laptop dnsmasq-dhcp[10279]: DHCPREQUEST(enp0s29f7u2u4) 10.0.0.168 1c:e6:2b:2f:b6:8f 
Mar  7 12:18:36 Riaqn-Laptop dnsmasq-dhcp[10279]: DHCPACK(enp0s29f7u2u4) 10.0.0.168 1c:e6:2b:2f:b6:8f Riaqn-iPhone
Mar  7 12:18:38 Riaqn-Laptop dnsmasq-dhcp[10279]: DHCPDECLINE(enp0s29f7u2u4) 10.0.0.168 1c:e6:2b:2f:b6:8f 
Mar  7 12:18:51 Riaqn-Laptop dnsmasq-dhcp[10279]: DHCPDISCOVER(enp0s29f7u2u4) 1c:e6:2b:2f:b6:8f 
Mar  7 12:18:51 Riaqn-Laptop dnsmasq-dhcp[10279]: DHCPOFFER(enp0s29f7u2u4) 10.0.0.186 1c:e6:2b:2f:b6:8f 
Mar  7 12:18:51 Riaqn-Laptop dnsmasq-dhcp[10279]: DHCPDISCOVER(enp0s29f7u2u4) 1c:e6:2b:2f:b6:8f 
Mar  7 12:18:51 Riaqn-Laptop dnsmasq-dhcp[10279]: DHCPOFFER(enp0s29f7u2u4) 10.0.0.186 1c:e6:2b:2f:b6:8f 
Mar  7 12:18:52 Riaqn-Laptop dnsmasq-dhcp[10279]: DHCPREQUEST(enp0s29f7u2u4) 10.0.0.186 1c:e6:2b:2f:b6:8f 
Mar  7 12:18:52 Riaqn-Laptop dnsmasq-dhcp[10279]: DHCPACK(enp0s29f7u2u4) 10.0.0.186 1c:e6:2b:2f:b6:8f Riaqn-iPhone
Mar  7 12:18:57 Riaqn-Laptop dnsmasq-dhcp[10279]: DHCPDECLINE(enp0s29f7u2u4) 10.0.0.186 1c:e6:2b:2f:b6:8f 
Mar  7 12:19:10 Riaqn-Laptop dnsmasq-dhcp[10279]: DHCPDISCOVER(enp0s29f7u2u4) 1c:e6:2b:2f:b6:8f 
Mar  7 12:19:10 Riaqn-Laptop dnsmasq-dhcp[10279]: DHCPOFFER(enp0s29f7u2u4) 10.0.0.187 1c:e6:2b:2f:b6:8f 
Mar  7 12:19:10 Riaqn-Laptop dnsmasq-dhcp[10279]: DHCPDISCOVER(enp0s29f7u2u4) 1c:e6:2b:2f:b6:8f 
Mar  7 12:19:10 Riaqn-Laptop dnsmasq-dhcp[10279]: DHCPOFFER(enp0s29f7u2u4) 10.0.0.187 1c:e6:2b:2f:b6:8f 
Mar  7 12:19:11 Riaqn-Laptop dnsmasq-dhcp[10279]: DHCPREQUEST(enp0s29f7u2u4) 10.0.0.187 1c:e6:2b:2f:b6:8f 
Mar  7 12:19:11 Riaqn-Laptop dnsmasq-dhcp[10279]: DHCPACK(enp0s29f7u2u4) 10.0.0.187 1c:e6:2b:2f:b6:8f Riaqn-iPhone

Any ideas?
-- 
Zesen Qian (钱泽森)