V 1.38 SSL VPN DNS bug

hORnZ

Good day,

After upgrading my flex700h to the latest (1.38) firmware, SSL VPN stopped to do any DNS resolution.

In VPN - SSL VPN, option DNS Server I have ZyWall. Used to work fine. When I check logs now of VPN client connected, I see this "ZyWall" is passed as is, while it has to be an IP instead. I have currently fixed it manually specifying interface IP, but automated testing shall be knocking Zyxel door.

2026-04-17 14:37:32.455452 PUSH: Received control message: 'PUSH_REPLY,route <masked>,dhcp-option ADAPTER_DOMAIN_SUFFIX local.domain,dhcp-option DNS ZyWALL,route-gateway <masked>,topology subnet,ping 10,ping-restart 120,ifconfig <masked>,peer-id 0,cipher AES-256-GCM,protocol-flags cc-exit tls-ekm dyn-tls-crypt,tun-mtu 1500'

PeterUK

Yes this does look like a bug that the SSL VPN is not pulling the Zywall DNS by DHCP like 192.168.51.1 when IP pool is 192.168.51.0/24 when set to zywall or zywall then custom or custom then Zywall

workaround is to set custom with 192.168.51.1 for DNS

GiuseppeR

I agree with @PeterUK you can set DNS as that workaround or declare them like 8.8.8.8

Zyxel_Melen

Hi @hORnZ @PeterUK @GiuseppeR

We have addressed this issue and will release the date code firmware next week. I will send it to you once release.