RT-AC68U Internet detection WAN setting

[banger]

Recently I have been suffering drops in PPP session when downloading a 1gb test file, the file gets to 800-900mb and fails because of session drop randomly. I have been trying to diagnose this for months with many routers.

Asus factory default PPP echo with Interval 6 and 10 Max failures. My ISP said this setting may be incorrect if I understand their email. Other options for Internet Detection are DNS Probe and Disabled. I am now thinking Disabled is the correct setting for my connection as the download takes a higher priority than the PPP Echo and PPP Echo is being swamped by the download.

Thoughts?

 

[ColinTaylor]

I would definitely try disabling PPP Echo and seeing if that makes a difference. It sounds like something that should be easy to test. If it does prove to be the problem you can think about what the best values to set might be.

 

[banger]

I forgot to mention, the drop is random so have setup a script to download the 1gb every hour and am now using BT Openreach modem the HG 612. Before I was using a ZyXel VMG-1312-B10A modem which syncs higher but I went back to basics with the modem. I will test with Disabled.

 

[ColinTaylor]

The only disadvantage that I can think of to having that option disabled is if (when?) the PPP link does genuinely go down the router won't detect it and therefore not restart the connection. (That's just me guessing)

With the default options of 6 seconds times 10 presumably it can go for 60 seconds without a response before it assumes there's a problem. Maybe your ISP could tell you what they think are the correct numbers if they're saying that's wrong. If your biggest download takes say 3 minutes maybe set the numbers to 20 seconds times 10.

 

[banger]

The only disadvantage that I can think of to having that option disabled is if (when?) the PPP link does genuinely go down the router won't detect it and therefore not restart the connection. (That's just me guessing)

With the default options of 6 seconds times 10 presumably it can go for 60 seconds without a response before it assumes there's a problem. Maybe your ISP could tell you what they think are the correct numbers if they're saying that's wrong. If your biggest download takes say 3 minutes maybe set the numbers to 20 seconds times 10.

I think I can test when the PPP drops by disconnecting the modem and watch the Syslog and see what happens, in fact I will try that.

I came across a discussion of a similar problem on google and the guy was advised that the BT advised settings are 4 4 to keep sessions alive. My ISP is advising disabled and test for 7 days or they can send an engineer but I doubt the engineer will be familiar with Asus routers.

 

[ColinTaylor]

I think the engineer visit would be because they think the connection is dropping because of noise on the line (which has nothing to do with the router). But I doubt they'll send an engineer out unless you are experiencing the same problem with the ISP supplied equipment.

 

[banger]

The answer to the re-connect question is yes it detects the session down within a few seconds and reconnects as soon as I plug the cable back in with the setting on Disabled and re-authorises the PPP.

 

[banger]

I've just rebooted the modem which takes about 30 seconds and it kept the connection alive. eg audio streams continued after a short break and download picked up where it left off. Maybe on to something here.

 

[banger]

The only disadvantage that I can think of to having that option disabled is if (when?) the PPP link does genuinely go down the router won't detect it and therefore not restart the connection. (That's just me guessing)

You were correct the session dropped this morning at 7.34 and didn't get detected so didn't reconnect so I guess echo PPP is to be tried with different values.

 

[banger]

What is the default settings for PPP Echo detection?

 

[ColinTaylor]

I believe it's interval=6 and failures=10.

https://github.com/RMerl/asuswrt-merlin.ng/blob/8559eb12e1801ab658e5210330d7a602a2d1a85a/release/src/router/shared/defaults.c#L1725

 

[banger]

Many thanks, it has dropped 3 times today under load. ISP is sending an engineer and I am hoping for a port swap as in the ISP session history page it says port error when it drops.

 

[banger]

Wrote to Openreach CEO detailing the fault and he has assigned a network engineer to the problem who called me today. Have also re-instated the ZyXel modem/router as it is BT approved to the line and tbh it feels a bit snappier on my PC with the AC68U as an AP.

 

[pcb]

Just throwing this out there since I haven't seen it mentioned here yet. I own an AC68U, although it's not currently in service, but I had a similar-sounding problem with my AC5300.

For weeks whenever I went to the web interface of the router, the Internet status reported on the Network Map page always said "Disconnected" even though clients were indeed able to access the internet. I was able to fix this by setting "Connect to DNS Server automatically" on the Advanced Settings > WAN page to NO, and then specifying alternative DNS servers (I used the google ones at the time, currently using the opendns ones).

I am NOT using PPP (have Automatic IP selected for connection type instead), but since you mentioned "DNS Probe" as a keep-alive option, I wonder if you could try selecting that and also overriding your DNS Server settings like I did to a known-good DNS provider near you?

 

[banger]

I already have my DNS set to cloudfare, but DNS probe doesn't work for me. When PPP drops and DNS probe is set the AC68U never detects the session is down and doesn't start the re-connect process. It's like setting disabled.

 

[banger]

Found out why DNS Probe might not work, Cloudflare has DDOS protection so may not accept pings.