VM hub vs ASUS AC88U

[Svalbaard]

Hi everyone. I was hoping to benefit from the combined wisdom of the forum on a weird issue I have recently started having. I thought I'd describe my current setup first...

I have a VM broadband connection, the hub itself has been set in modem mode for the last couple of years (i.e. since I've had it). Behind this is my AC88U which as you'd expect, provides all of the actual networking grunt and runs a fairly up to date version of the Merlin ASUSwrt derivative.

Up until Monday evening, all has been well with no issues whatsoever, when for no apparent reason I lost all connectivity to the internet and WWW, and I'm struggling to work out why.

So, so far I have taken the following steps in terms of diagnosis :

1. I have reverted the VM hub back to router mode, stood up a test wifi network on it and connected both phone and laptop to it - in this config, both devices seem to access the internet without any issues. On this basis I'm not sure it is an actual VM or hub issue.

2. I've then left the VM hub in router mode, turned off the test wifi and then restarted the ASUS router. In this configuration I can't access the internet via wifi, but can access the ASUS router admin pages, VM hub admin web page (192.168.0.1), and I can also seemingly ping the VM WAN IP address assigned.

3. Reverting the VM hub back to modem only mode, the situation is the same as in point 2 above, albeit that the hub IP address is then 192. 168.100.1.

I've not been able to try to connect via cabled ethernet as I don't have an RJ45-USB adapter (yet), but I have noticed that when I select "network map" on the ASUSWRT admin page, it briefly does show the VM WAN IP address, before swiftly reverting to "disconnected".

Nothing has changed on the ASUS router since I upgraded to a newer Merlin firmware a few weeks ago, but even then, it had been working just fine. My next step was to perhaps do a factory reset on the ASUS and to try again from scratch?

I was wondering if anyone had any ideas? I've not had the chance to post any router logs yet, but I suspect a DHCP issue or something.

Does anyone have any other initial thoughts?

Many thanks in advance.



Sval

 

[ColinTaylor]

Check the status of your VM service. https://my.virginmedia.com/faults/service-status

 

[Svalbaard]

Check the status of your VM service. https://my.virginmedia.com/faults/service-status

Hi, thanks. But it is reporting no issue, and also see point 1 of my initial diagnosis steps in the OP.

 

[ApexRon]

... I have noticed that when I select "network map" on the ASUSWRT admin page, it briefly does show the VM WAN IP address, before swiftly reverting to "disconnected".

I believe this is the key to your issue, a problem with the connection between the modem and the router. This could be a physical issue or with auto-negotiation.

1. Try a new, high quality Ethernet cable
2. What causes an auto-negotiation issue is an incompatibility in the firmware of either device to provide that function. The easiest way to resolve an auto-negotiation issue is to disable it on either device and choose a fixed speed and duplex mode. I doubt you’ll be able to do that on ASUS.

 

[ColinTaylor]

I had an issue with my VM line recently where the modem couldn't hang onto the sync for more than a few minutes. The effect of this in modem mode meant that the router lost its internet connection, whereas in router mode the hub would tolerate the constant disconnect/reconnects and the user perceived it just as a slow/intermittent service.

Check the hub's network log at 192.168.100.1 and also the router's syslog for clues.

 

[Svalbaard]

Thanks everyone for the replies but the actual answer for this is a bit more simple than I had thought, but odd in that I'm still not sure I understand either why or how this has suddenly started happening. I did try another cable, but that wasn't it.

So I kept the VM hub in router mode and then managed to dig out of the loft a long forgotten Belkin G wireless router that I did some reconfiguration to, and then connected up. This seemed to work perfectly, so this ruled out any real issues with the Virgin service, or their Superhub itself. The downside of this is that the Belkin, as a very early and basic plug&play router doesn't really allow any lower level analysis of settings for comparison between itself and the ASUS AC88.

What it appears to be is around the WAN >> WAN DNS settings. Up until it going wrong, I had always had the "Connect to DNS Server automatically" field set to NO, and had my own choice of DNS supplier in there. This now no longer seems to work, and will only connect to the wider internet when I set this field to "YES". Which I do not want.

Quite why this has stopped working is anyones guess as nothing has changed, and the DNS IP addresses are still valid.

I'll keep looking into this over the weekend.

 

[ApexRon]

An unreachable DNS server should not cause the symptoms you described namely the disconnection of the WAN link. Anyway, I use Google and Open DNS.

 

[Svalbaard]

I know. That's why I described it as "odd". I'm going to keep playing with the configuration permutations, and with some different DNS providers over the weekend just to be sure.