AC88U internet drops when PC crashes

CntrlAltDel

New Around Here
Asus RT-AC88U
Merlin 386.7_2

Hi everyone,

I'm having this very strange issue that when my PC crashes the router no longer provides an internet connection. I can see it's still connected but it seems like it just drops all packets. I've contacted my ISP and they've confirmed there are no outages or anomalies on my line.
I've tried doing fresh installs of stock and fresh installs of merlin. This behaviour still happens and the internet drops to all devices in the house wireless and wired.

We have power outages at times, my PC is on a battery. When drawing 400w+ of power it will switch off and that causes the issue with internet dropping (without disconnecting on router). The router and ONT are both on their own UPS and remain uninterrupted.
In terms of my PC crashing, I test OC's and it crashes from time to time, when it crashes the internet drops same as above.

Would anyone happen to know what could be the cause of this strange behaviour?

When this happens I will have to restart the router and ONT for the internet to behave normally again.

2022-11-05 19_14_22.png
 
Last edited:

L&LD

Part of the Furniture
Is your ISP modem/ONT and router (switches) also on a UPS?

This sound like a possible (brownout) power issue to me.
 

CntrlAltDel

New Around Here
Is your ISP modem/ONT and router (switches) also on a UPS?

This sound like a possible (brownout) power issue to me.
The ONT and router are on their own UPS.

The desktop is on a lithium battery. It isn't line interactive so when there's a power outage there's a shutdown and restart that happens.

The thing is this doesn't just happen when there's power outages. This happens when my desktop crashes too. The desktop will BSOD when I'm testing OC's and this will happen anyway even though the power is fine.

Though the internet is still up none of the devices are able to do anything on the internet. In order to resolve this I have to restart both ONT and router
 

L&LD

Part of the Furniture
Then maybe the issue is when the desktop crashes, the LAN port is still active and causing your network troubles.

The indicated fix is to get a UPS that can handle more than 400W of continuous use.

Is your computer a laptop or a desktop? Can you get a more efficient (Gold+ or better) power supply? Can you undervolt your system to lower the total power used?

This still doesn't look like a router issue, per se, to me.
 

CntrlAltDel

New Around Here
Then maybe the issue is when the desktop crashes, the LAN port is still active and causing your network troubles.

The indicated fix is to get a UPS that can handle more than 400W of continuous use.

Is your computer a laptop or a desktop? Can you get a more efficient (Gold+ or better) power supply? Can you undervolt your system to lower the total power used?

This still doesn't look like a router issue, per se, to me.

https://www.super-flower.com.tw/product-data.php?productID=81&lang=en
This is the PSU I use. It's very good.

Regarding the undervolting question, I've reverted back to stock to monitor behaviour of this occurring.

Regarding getting a UPS that can handle more than 400w, I've added an actual line interactive UPS in between the lithium battery and the desktop the crash inbetween power being lost on the grid shouldn't cause any issues now on my side.

Would just like to know what on earth is going on with the network.

I can still reach the Asus router page and ping any address, google etc. I just cant load any pages because "refused to connect" and the only way to resolve it would be that I'd need to restart both ONT and router then the internet is as per normal.
 

L&LD

Part of the Furniture
Then maybe the issue is when the desktop crashes, the LAN port is still active and causing your network troubles.

If the crash leaves your LAN port in an unknown state, that may be what is causing the issue.

Equipment is rated to work when other equipment is behaving as expected. Yours is not (when the issue surfaces). They can't be expected to work when other systems crash (while connected to them).

If the PSU is of decent quality (and specs don't guarantee it is...), then something else is 'weak' in the system. Either the motherboard, power circuitry/components, RAM, SSD, GPU, or settings for one/all of those.

Test it by connecting via WiFi if you can (if you don't have WiFi on board, use a spare router in Media Bridge mode). When it crashes, does it still take the network down?
 

CntrlAltDel

New Around Here
If the crash leaves your LAN port in an unknown state, that may be what is causing the issue.

Equipment is rated to work when other equipment is behaving as expected. Yours is not (when the issue surfaces). They can't be expected to work when other systems crash (while connected to them).

If the PSU is of decent quality (and specs don't guarantee it is...), then something else is 'weak' in the system. Either the motherboard, power circuitry/components, RAM, SSD, GPU, or settings for one/all of those.

Test it by connecting via WiFi if you can (if you don't have WiFi on board, use a spare router in Media Bridge mode). When it crashes, does it still take the network down?
That's actually a brilliant idea. I do have a spare router that can run in media bridge. I also have an Intel Gigabyte CT PCI-E card on hand that I can use to drill down to what's causing the issue.
I'll also test with wireless AC card to see if it's still apparent.
The strange thing is I check the logs when this happens and I cant see anything standing out.
 

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