Not sure if this is the right place to post, first time. I know practically nothing about networking, but I had to install openwrt because the SQM on my WRT1900ACS v1 sucks connected to my ISP's modem that is in bridge mode. I have everything set up but I've run into an issue. My ISP changes my IP address every 12 hours, normally I have like 6ms or 7ms ping when I ping 8.8.8.8. Right after the IP address changes I get 35-40ms when I ping 8.8.8.8 and this happens until I reboot my router. What could cause this? I am on OpenWRT 19.07.08, but the same thing happens on the latest version 21.02.
Can you better try to do an mtr 8.8.8.8 instead? You might need to install it. opkg update; opkg install mtr
Try it before and after the IP changes.
This time the IP address changed about 6 times I believe, after the 6th time the problem returns. So I had to go to Networks -> Interfaces and restart the PPPoE protocol to go back to normal..
BEFORE
AFTER
As you can see from the output, the problem occurs on the 4th hop. This is out of your control and not much OpenWrt can do there. You can inform your ISP and maybe they can help you troubleshoot.
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But if the problem is coming from my ISP then why am I able to fix the problem with just a simple restart of my openwrt router's PPPoE connection? That's what I'm failing to understand here. I don't have to touch my ISP's modem, I just reset the PPPoE client on the openwrt router and the ping goes back to normal.
So I assume that you get different IPs on each PPPoE reconnection? Some ISPs use different routing for different IPs in their possession. Try to note down the IPv4 address your router gets assigned as well as the output of mtr -ezb4w -c 60 dns.google (this invocation results i a somewhat richer output) there might be a relation to the actual routing as well as the experienced RTT.
BTW, it makes sense to redact your own pubic IP address (if you fear to be attacked by someone scrapping this forum for addresses, during the 12 hours that address is assigned to your link) but please do not redact the later hops as it makes the mtr results hard to interpret.
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So I just looked into this and the first time I hit restart on the PPPoE connection in OpenWRT it seems that my Ipv4 address did change. But after restarting 2-3 times after that it did not change..
The internet is not a static network, there are 1000 reasons why your path to dns.google varies:
- based on traffic your ISP may assign you to different resource group with different routes,
- ISP has a problem so they re-route traffic to alternative path,
- ISP inter-connect to other ISP can dynamically change based on traffic, commercials etc
- etc etc etc
there is no way your home router running owrt can control this.
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Well, keep monitoring if the problem correlates with IP addresses from specific subnets. If no not much you can do, if yes you can at least badger your ISP (with very dim chances of them actually changing anything 
)
BTW, it is nicer to just copy and paste the text output from a terminal into the forum, formatted as "preformatted text" or for multi line output by adding a line with just three backticks before and after your text. Here is what you would type:
```
your text
one more line
yet another line
```
here is how it will then look
your text
one more line
yet another line
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