Asus RT-AX86U PRO w/ Merlin - Entire Router Reboots when one user connects to the VPN, but only when 2.4GHz WiFi is turned on

[sojomy]

This is the weirdest issue I've ever seen with a router. When only one client connects to our Asus RT-AX86U Router with the newest Merlin firmware (and the 2nd to newest) using the OpenVPN client, the entire router reboots like someone turned it off and back on again. But it only does this to one client, several others can connect with no issue. It also only does it when the 2.4GHz radio is enabled. If I disable just that functionality under the Wireless->Professional settings, the problem goes away!


Here's the point of issue
• I have a single user with a Windows 10 Laptop who connects to the OpenVPN TAP Server from home using the OpenVPN 2.5.9 client
• Once she connects, she can ping the internal LAN IP of the router for 0-2 seconds, then it starts failing
• This is because after she connects, within 2 seconds, the router at the office reboots like someone turned it off and back on
• I have to wait 60-90 seconds for the router to boot back up before I can log back into it
• Not only did the router reboot, but the system log starts with normal startup entries, but the router's clock was reset "May 5 00:05:10".
• After a few seconds during the system boot process, the NTP sync happens and the time is set back to the correct time
• No other settings in the router are reset except for the date & time
• I can connect to the same OpenVPN server from several other clients using the exact same client config file, same VPN User account, and same OpenVPN client version - just different computers
• If I disable the 2.4GHz radio on the router, the problem goes away for the client that is having an issue, but then none of their 2.4GHz-only WiFi devices in the office can connect to the network wirelessly.
• If I leave the 2.4Ghz radio enabled, but disable the 5.0GHz radio, the problem still happens, so it's definitely just the 2.4GHz radio
• I have already tried disabling Smart Connect, and changing the 2.4GHz radio to N-Only, and no Legacy support, but no change

There are 30 other settings for the 2.4GHz radio and I don't want to just start changing things. Does anyone have any idea what the 2.4GHz radio has to do with the OpenVPN server in the router, and what I can do to get both working at the same time? Any help is appreciated!

 

[MXThaurus]

I had a similar problem on merlin beta 388.4 , after installing Flexqos my router keeps reeboting when a certain client was connected to 2.4Ghz, probably a bug. What Merlin version are you using, stable or beta?
To solve i switch back to merlin 388.2_2 and problem was gone for me. Now i have seen that merlin 388.4_0 is stable from yesterday, try to update, there's an updated version of OpenVPN to 2.6.5, maybe it can help.
If anything will help, try last stable official asuswrt and update us here. Remember to do an hard reset or better a nuclear reset when you switch software.

 

[sojomy]

@MXThaurus thank you for the reply. I was actually using 388.2_2 until yesterday when we tried to start using the VPN. After I setup the VPN, exported the client config file, and copied it to the client that was already using OpenVPN 2.5.6, that's when we discovered the problem. I updated the OpenVPN client software to the newest version 2.6.6, and the problem stayed. I have OpenVPN 2.5.9 on my computer, and I can connect to the VPN with no problems and no reboots, so I downgraded the OpenVPN client software on my other user's computer to 2.5.9, the same version I am using. I still had a problem, so I upgraded the router's firmware to the new Merlin firmware of 388.4 that was just released yesterday. Nothing seems to fix the router reboot issue except to disable the 2.4GHz radio.

The client called this morning because 9 of their older devices are not working on WiFi with the 2.4GHz radio disabled, so I have to turn it back on. But that means the office manager cannot connect to the VPN now. @RMerlin any thoughts? Anything else you can think of that I could change with the wifi settings to possibly keep the 2.4GHz enabled while still allowing the user to connect to the router's VPN without the router rebooting?

Also, I forgot to mention earlier that I have to use TAP because the user needs to access network shares on 2 computers.

 

[MXThaurus]

@MXThaurus thank you for the reply. I was actually using 388.2_2 until yesterday when we tried to start using the VPN. After I setup the VPN, exported the client config file, and copied it to the client that was already using OpenVPN 2.5.6, that's when we discovered the problem. I updated the OpenVPN client software to the newest version 2.6.6, and the problem stayed. I have OpenVPN 2.5.9 on my computer, and I can connect to the VPN with no problems and no reboots, so I downgraded the OpenVPN client software on my other user's computer to 2.5.9, the same version I am using. I still had a problem, so I upgraded the router's firmware to the new Merlin firmware of 388.4 that was just released yesterday. Nothing seems to fix the router reboot issue except to disable the 2.4GHz radio.

The client called this morning because 9 of their older devices are not working on WiFi with the 2.4GHz radio disabled, so I have to turn it back on. But that means the office manager cannot connect to the VPN now. @RMerlin any thoughts? Anything else you can think of that I could change with the wifi settings to possibly keep the 2.4GHz enabled while still allowing the user to connect to the router's VPN without the router rebooting?

Also, I forgot to mention earlier that I have to use TAP because the user needs to access network shares on 2 computers.

We will wait for experts but meanwhile in your situation i would do a nuclear reset with last merlin firmware (no backups), config all again and give it a try.

 

[RMerlin]

If the router spontaneously reboots even after a factory default reset, then I would suspect a hardware issue - possibly with the power brick.

 

[sojomy]

If the router spontaneously reboots even after a factory default reset, then I would suspect a hardware issue - possibly with the power brick.

@RMerlin I appreciate the response! But would that explain why 3 external computers can connect to the OpenVPN server in the router with no issue (and at the same time), but the second the problem client connects, the router reboots? They're all using the same version of OpenVPN client, and all using the same client config file.

I thought about going to get another router from the store, but it's a 1 hour drive each way to the office. Is the "factory reset" option in the router management the same as using the hardware factory reset button, or are there any differences that the hardware factory reset do that the software factory reset does not do?

 

[RMerlin]

But would that explain why 3 external computers can connect to the OpenVPN server in the router with no issue (and at the same time), but the second the problem client connects, the router reboots? They're all using the same version of OpenVPN client, and all using the same client config file.

Maybe, maybe not. Hardware issues can look very random sometimes. As an example, a couple of years ago I was at a customer's place. Her PC would self reboot the instant she opened her DVD drive tray. The issue turned to be her power supply - not the most intuitive source... That's why I never discount it when encountering these kind of random issues. OpenVPN largely running in userspace, it's highly unlikely to be able to cause a kernel level crash that leads to a reboot, unless it's something related to networking itself.

Check the system log to see if there are any crashlog entries following the reboot.

Is the "factory reset" option in the router management the same as using the hardware factory reset button, or are there any differences that the hardware factory reset do that the software factory reset does not do?

Make a backup of both your settings and the JFFS partition (just in case), then use the factory default reset option found on the web interface.