RT-AC86U disconnecting when downloading

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Riscy

New Around Here
Hi guys,

Bit stumped by my problem here. I an ASUS RT-AC86U which has been fine running a 285/25 HFC connection for a while now. I recently was able to upgrade speed to 1000/50 and some problems have come to light. The speed is fine when speed tested; I get up to 940/48 with some expected fluctuations here and there. The main problem though is pretty soon after I start downloading something at high speed my PC seems to lose connection to the router. I have to 'trouble shoot problems' my network connection which does bring it back. The stated error was '"the default gateway is not available". The router remains working and available for other devices via wifi the entire time.

This is only when downloading fast. I've had a look at the routers CPU usage and temps and they seem reasonable. So far troubleshooting I have:

- Disabled adaptive QoS
- Updated to latest merlin firmware
- Checked MoBo NIC drivers up to date
- Tried USB gigabit NIC
- Tried standard ASUS firmware
- Factory reset settings
- Replaced both Modem > Router and Router > PC cables. Both cat6.

Nothing has helped. 30 seconds to a minute into a download and the connection dies and throughput goes to 0. NIC needs to be restarted to work. All QoS is disabled. I don't think it's my PC as it can quite happily transfer files via the router at gigabit speeds all day long ~110MB/sec.

Any ideas troubleshooting this further? Router is only a year old roughly.

Thanks
 

follower

Senior Member
Hi guys,

Bit stumped by my problem here. I an ASUS RT-AC86U which has been fine running a 285/25 HFC connection for a while now. I recently was able to upgrade speed to 1000/50 and some problems have come to light. The speed is fine when speed tested; I get up to 940/48 with some expected fluctuations here and there. The main problem though is pretty soon after I start downloading something at high speed my PC seems to lose connection to the router. I have to 'trouble shoot problems' my network connection which does bring it back. The stated error was '"the default gateway is not available". The router remains working and available for other devices via wifi the entire time.

This is only when downloading fast. I've had a look at the routers CPU usage and temps and they seem reasonable. So far troubleshooting I have:

- Disabled adaptive QoS
- Updated to latest merlin firmware
- Checked MoBo NIC drivers up to date
- Tried USB gigabit NIC
- Tried standard ASUS firmware
- Factory reset settings
- Replaced both Modem > Router and Router > PC cables. Both cat6.

Nothing has helped. 30 seconds to a minute into a download and the connection dies and throughput goes to 0. NIC needs to be restarted to work. All QoS is disabled. I don't think it's my PC as it can quite happily transfer files via the router at gigabit speeds all day long ~110MB/sec.

Any ideas troubleshooting this further? Router is only a year old roughly.

Thanks
Have you changed the cable?
 

Riscy

New Around Here
Router log:

May 9 18:54:51 kernel: eth4 (Ext switch port: 3) (Logical Port: 11) Link DOWN.
May 9 18:54:51 kernel: br0: port 4(eth4) entered disabled state
May 9 18:54:53 kernel: eth4 (Ext switch port: 3) (Logical Port: 11) Link UP 1000 mbps full duplex

Reinstalled mobo LAN driver and updated chipset driver. No help.
 

Riscy

New Around Here
OK seems like it's not the router. Same thing with modem connected direct to PC. Thanks anyway.
 

OcramSagev

Occasional Visitor
Hi guys,

Bit stumped by my problem here. I an ASUS RT-AC86U which has been fine running a 285/25 HFC connection for a while now. I recently was able to upgrade speed to 1000/50 and some problems have come to light. The speed is fine when speed tested; I get up to 940/48 with some expected fluctuations here and there. The main problem though is pretty soon after I start downloading something at high speed my PC seems to lose connection to the router. I have to 'trouble shoot problems' my network connection which does bring it back. The stated error was '"the default gateway is not available". The router remains working and available for other devices via wifi the entire time.

This is only when downloading fast. I've had a look at the routers CPU usage and temps and they seem reasonable. So far troubleshooting I have:

- Disabled adaptive QoS
- Updated to latest merlin firmware
- Checked MoBo NIC drivers up to date
- Tried USB gigabit NIC
- Tried standard ASUS firmware
- Factory reset settings
- Replaced both Modem > Router and Router > PC cables. Both cat6.

Nothing has helped. 30 seconds to a minute into a download and the connection dies and throughput goes to 0. NIC needs to be restarted to work. All QoS is disabled. I don't think it's my PC as it can quite happily transfer files via the router at gigabit speeds all day long ~110MB/sec.

Any ideas troubleshooting this further? Router is only a year old roughly.

Thanks
I recently bought an used AC86U from Amazon and I was having the same problem, it was driving me nuts (and my other 1/2). It took me a while to figure out what it was causing the disconnects. These were my troubleshooting steps:
1.- I had a Western Digital 4TB that had a mix of NTFS and HFS partitions, I deleted the HFS partitions. I also disconnected the USB HDD. i checked the USB HDD for errors with my computer.
2.- Turn off Wifi 2.4Ghz (yes, even though I was seeing the problem with ethernet connections).
3.- Again, I assume we are talking non-wifi connections (since you are reporting 900+ Mbps speeds). try another cable that is category 5e or higher.
4.- Are you using DDNS? Try disconnecting it. (My log was showing the router was connecting regularly to ddns server, every 30 min or so and the log showed a warning)
5.- Disable IPV6.

In the end, this is what worked for me
1.- Hard factory reset
2.- re-Config router (not via a config file).
3.- Removed the HFS partitions in the USB HDD.
So I am not sure if something in the config file got corrupted or the firmware did not like the HFS file .. Now mine is running rock solid.

You can turn on the debug and debug in system log. In the logs, look for "Kernel Panic".. usually if there is a kernel panic, the log will say what is causing it. Or you can post it here and some of the gurus may be able to help.
 

Riscy

New Around Here
Thanks. Turned out my problem was in windows. Seems it's been a common issue for a while. At slow download speeds it's fine but past a certain point it will disconnect the adapter. I tried about 10 fixes but nothing worked so I reformatted and that fixed it.
 

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