DNS failures when there are 2 wan
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Hello, I have relative knowledge of networks but there is something that I do not understand and if there is someone who understands why this happens, please help me and thank you in advance. I have 2 Wans from different providers and both are always connected but DNS 1.1.1.1 goes through the Wan. 1 and dns 8.8.8.8 goes through wan 2 and I don't understand why if the router mode is in backup and that shouldn't happen. When wan 2 fails, so does dns 8.8.8.8 and whoever uses that dns is offline
WAN1=200.8.16.1
WAN2=10.110.0.1
All of them should only go through the main wan, that is, wan2, but dns 8.8.8.8 does not do so.
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@Clive_A Sorry for not updating in time. I don't know if it is a problem but when the dns that use or are configured on the side of the wan, said dns is anchored to that wan. Example: If I configure or my isp gives me dns 8.8.8.8 on wan 1 and said wan goes down The balancer will begin to divert packets to wan 2 but dns 8.8.8.8 will not. That one will continue trying to go through wan 1. In my case the solution was to change the DNS of the wan to one that I do not use on my network. Sorry if there are any translation errors
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Hi @Josvell
Thanks for posting in our business forum.
Josvell wrote
@Clive_A Yes, exactly. If wan 1 has 8.8.8 8 and wan 2 has 1.1.1.1 in its configuration. If wan 1 stops having connectivity (internet) so will dns 8.8.8.8. If I maintain an infinite ping to youtube.com and another ping to 8.8.8.8 and cause the failure, both pings stop responding but after 15 seconds the ping from youtube.com responds again but 8.8.8.8 does not respond again and at the same time time Doing a traceroute to 8.8.8.8 shows how it tries to go through wan 1 even though the er605 knows it is down. NOTE: This happens when you cause it to have no connectivity (internet). Because if you cause the failure by physically disconnecting WAN 1, this failure never occurs. I apologize if there are any translation errors.
Confirmed that this is a known issue. Dev is aware of this issue and will optimize this in future firmware updates.
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@Tedd404 It is the unmodified routing table. Everything you see there was done by the er605 automatically. When I remove wan1 (I disconnect it) the routing table is automatically modified and 8.8.8.8 goes from wa1 to wan2 as it should.
I determined this failure because I keep a PC pinging 8.8.8.8 -ta both dns and when it caused a failure in wan1 that dns stops working until I physically disconnect wan1
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@Josvell I update a little information. Today I decided to restore the factory settings of the er605 and test if the dns changed when one of the two wans failed and what a surprise. Exactly the same thing happens, sometimes there are dns that get stuck. When the main wan fails, the er605 must resend everything through the backup wan and this is the case of dns 1.1.1.1 but dns 8.8.8.8 gets stuck in the main wan and although detect that this drop does not change. The rest of the dns work fine. When the main wan fails the dns stop responding for a few seconds and have ping again seconds later. But the dns 8.8.8.8 never changes. I performed a traceroute to 8.8.8.8 and they stuck at the ip of my main wan and did not wants to change to the backup wan Configuration is discarded on my part since I reset the er605 from the factory
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Since those aren't your ISP DNS servers, where did you configure those DNS server IPs...i.e. in the LAN subnet(s)?
You should also be able to create Policy Routing rules to force say 8.8.8.8/32 via WAN1 (but tick the box for failover) and a similar policy for 1.1.1.1/32 via WAN2.
Something like this, where 'Special' is 8.8.8.8
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Josvell wrote
@Tedd404 It is the unmodified routing table. Everything you see there was done by the er605 automatically. When I remove wan1 (I disconnect it) the routing table is automatically modified and 8.8.8.8 goes from wa1 to wan2 as it should.
I determined this failure because I keep a PC pinging 8.8.8.8 -ta both dns and when it caused a failure in wan1 that dns stops working until I physically disconnect wan1
Still curious about how you verified it. Does not seem to relate and make sense to me. Ping does not make sense but test the backup integrity.
How does it verdict your dns? What and why they relate?
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Hi @Josvell
Thanks for posting in our business forum.
Is there an update to your verification process? Please paste some screenshots and other information you think might help.
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@Clive_A Sorry for not updating in time. I don't know if it is a problem but when the dns that use or are configured on the side of the wan, said dns is anchored to that wan. Example: If I configure or my isp gives me dns 8.8.8.8 on wan 1 and said wan goes down The balancer will begin to divert packets to wan 2 but dns 8.8.8.8 will not. That one will continue trying to go through wan 1. In my case the solution was to change the DNS of the wan to one that I do not use on my network. Sorry if there are any translation errors
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@JosvellLA It's on my secondary account and I had to respond because this account was having problems. but I'm writing my answer here again
@Clive_A Sorry for not updating in time. I don't know if it is a problem but when the dns that use or are configured on the side of the wan, said dns is anchored to that wan. Example: If I configure or my isp gives me dns 8.8.8.8 on wan 1 and said wan goes down The balancer will begin to divert packets to wan 2 but dns 8.8.8.8 will not. That one will continue trying to go through wan 1. In my case the solution was to change the DNS of the wan to one that I do not use on my network. Sorry if there are any translation errors .
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Hi @Josvell
Josvell wrote
@JosvellLA It's on my secondary account and I had to respond because this account was having problems. but I'm writing my answer here again
@Clive_A Sorry for not updating in time. I don't know if it is a problem but when the dns that use or are configured on the side of the wan, said dns is anchored to that wan. Example: If I configure or my isp gives me dns 8.8.8.8 on wan 1 and said wan goes down The balancer will begin to divert packets to wan 2 but dns 8.8.8.8 will not. That one will continue trying to go through wan 1. In my case the solution was to change the DNS of the wan to one that I do not use on my network. Sorry if there are any translation errors .
You mean 8.8.8.8 will not be switched by the link backup?
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