I recently have configured a Peplink 310 for a client of mine located in Suriname, in South American. Since then we’ve had constant, but intermittent, DNS failures and timeouts. I suspect something is wrong with the Peplink, but can’t rule out coincidental issues with DNS within the country. (On the other hand, we’ve not see DNS problems there for the past 3 years, just once the Peplink went into place).
The config is a bit unusual on the WAN2 port. I cannot reconfigure the internet router (DSL) to do an unnumbered connection (no NAT) so I’ve set up the Peplink to do IP Forwarding on the WAN2 connection. I put a 192.168.12.x/24 address on WAN2 and on the LAN port of the WAN2 router. All NAT is done in the WAN2 router, and that router has only had it’s private IP address changed (to match the WAN2 port). The WAN2 router is doing a lot of port forwarding of inbound connections to a firewall on the inside of the Peplink, and I didn’t want to try to redo all of those settings to forward to addresses on the WAN2 port of the Peplink. I just put in a static route on the WAN2 router to point to WAN2 address of the Peplink to get to the LAN side of the Peplink so inbound data comes in to the exact same addresses it did before. Inbound traffic is working fine on the WAN2 side. Essentially I put the Peplink in between the old router and the old firewall and gave the LAN side the address of the old router so I didn’t have to redo the firewall addressing.
The WAN1 port is configured more typically. It is doing NAT and has multiple public IP addresses configured. Static NAT is configured on the Peplink and several inbound connections are defined which point to addresses on the firewall connected on the LAN side. (That firewall is doing dynamic and static NAT and has been working fine for years).
OK - symptoms that occurred with the installation of the Peplink. Almost immediately we started seeing email failures trying to send out. (550 host unknown). Browsing (through a proxy) became slow as well. Firewall, pointing to two internal DNS servers and the DNS proxy on the Peplink shows intermittent but frequent DNS ‘down’ status.
I started testing from the inside using NSLOOKUP. Eventually determined that it wasn’t possible to get DNS working outside the ISP’s DNS servers on the WAN2 side, and connections to the ISP’s DNS servers themselves were very unreliable at best. This was not true before inserting the Peplink between the ISP’s router and the firewall.
On the WAN1 side, DNS was working better. WAN1 is a faster link, but a new ISP, and we have no history of reliability.
Eventually I found that configuring the DNS proxy on the Peplink gave to least unreliable results, and I enabled the option to forward to Google DNS servers in the event of failure of the WAN1 and WAN2 DNS servers. And looking at the Status, Active Sessions on the Peplink sometimes shows 20-25 DNS connections to 188.8.131.52 (Google), indicating that the local DNS services have failed. When I see these connections, it generally means that DNS is failing completely, and the connections to 184.108.40.206 are just attempts at DNS rather than successful attempts.
I’ve tried using Service Forwarding of DNS to the proxy both on and off. I’ve configured the internal DNS servers to point to the Peplink LAN address as the main forwarder.
Due to DNS not working at all through WAN2, I’ve set up an Enforced Outbound Policy to send all DNS requests out the WAN1 side.
I’ve hooked up a test laptop on the WAN1 side, and done some preliminary DNS testing there. DNS seems fine when not going through the Peplink on the WAN1 side.
We’ve now had a week of frustration with bounced emails and slow browsing. I can’t think of anything else to try on the Peplink, and I’m wondering if a firmware revision is the only fix. The firmware (Balance 310) on the Peplink now is 5.3.12 build 1150.