MerlinWRT 386.4 DHCP problems

[dominik]

Hello, I just tried to switch from latest asus firmware to MerlinWRT on my RT-ac86u - mainly because of wireguard and entware.
I followed this: https://github.com/RMerl/asuswrt-merlin.ng/wiki/Installation - and just rebooted before uploading firmware, according to this doc nothing special was needed to switch.
It flashed without any issue and all settings were right on place, the only thing I noticed was turned off openvpn server, but new version has much more options. I just turned that on and everything was ok.

Later, next day I installed entware and wireguard, tested that and it was way easier than openvpn for setup and use it on mobile devices.

I was able to connect via wireguard on external network and access router admin panel via it's internal ip. Great and much easier than OpenVPN. I needed to add some usb3 drive for entware but it installed with no problem just like in docs.

Then I noticed that some devices are disconnected from network and they are not able to reconnect anymore. Checked few of them and quickly discoved that they autenticate but can't get IP or anything from DHCP server. On mobile phones it stuck at "obtaining ip address". With manual ip setup they were able to connect to wifi and Internet.
I checked manu threads on dhcp, tried to alter many options on lan, wan, vpn.. nothing helped
Also there was no clue in logs, all dhcp leases eventually were empty and nothing could connect automatically.

Home router without dhcp is not much usable, of course I got idea to just turn off dhcp and run some dhcp on kubernetes, but it would take some time to find good services and configure it. I found one thread about similar issue and advice to hard reset device, I still didn't wanted to lose all settings. Instead of that I decided to do "downgrade" to asus original firmware. That process was successful, and DHCP started to work again. Bye wireguard and entware

Ok, I got reverted router to original firmware, all basic stuff works now, but I still would like to get those two features. Any idea what was wrong on this upgrade? Anything else I should try other than hard reset right before (or after) upgrade? Anyone tried 386.4 on AC86U with no dhcp problems?

 

[ColinTaylor]

I can't say I've heard of that problem. The general advice for strange situations like this is to do a hard reset and manual setup, particularly when moving from stock to Merlin for the first time. The VPN implementation in Merlin's current release is significantly different than stock so I'd plan on doing a hard reset for that alone.

You can always take a backup of your current setup (Administration - Restore/Save/Upload Setting) before trying the reset. If it makes no difference you can restore back to where you were before.

 

[pinkgrae]

Anyone tried 386.4 on AC86U with no dhcp problems?

I've been running 386.4 on my AC86U since the firmware was released: no dhcp issues.

 

[dominik]

I've been running 386.4 on my AC86U since the firmware was released: no dhcp issues.

Thanks for reply, have You upgraded from last Asus firmware or earlier? I wrote here because this case can help some other people who would like to switch to merlinwrt. Maybe someone has idea what else should I check and how to diagnose this issue (or maybe fix it).

I can't say I've heard of that problem. The general advice for strange situations like this is to do a hard reset and manual setup, particularly when moving from stock to Merlin for the first time. The VPN implementation in Merlin's current release is significantly different than stock so I'd plan on doing a hard reset for that alone

As I said I found one thread with similar issue and it ended with reset so I know that this may fix it
Before I try that do You think it's worth to try to diagnose and fix that? I can yet again flash merlin and probably same thing won't work. VPN was obvious thing to change and easy to fix (just turning #1 server on, all data were ok). DHCP is bit harder to diagnose and and I literally tried to alter almost all options looking for something that may fix it with no luck. I consider this as serious problem for less advanced users who will hit issue few hours later when no new IP will be created.
Reset... what is best procedure for that? Should I use router button or the one in GUI? Or maybe it's better to do that via SSH? Can You please let me know what and how can I clear everything?

You can always take a backup of your current setup (Administration - Restore/Save/Upload Setting) before trying the reset. If it makes no difference you can restore back to where you were before.

Are those settings some plain text files that I can edit? I don't care about most of settings except pppoe data, dhcp, port forwarding etc. I didn't wanted to transfer something that may brake that DHCP.

Thank You for help and replies

 

[ColinTaylor]

Reset... what is best procedure for that? Should I use router button or the one in GUI? Or maybe it's better to do that via SSH? Can You please let me know what and how can I clear everything?

Do a hard reset, or use the option in the GUI (Administration - Restore/Save/Upload Setting > Factory default) with the "Initialise" box ticked. Obviously the reset must be done after installing the new firmware and not before. Don't attempt a reset through SSH.

[Wireless Router] ASUS router Hard Factory Reset - Method 2 | Official Support | ASUS Global

Are those settings some plain text files that I can edit?

No they are not editable.

 

[pinkgrae]

Thanks for reply, have You upgraded from last Asus firmware or earlier?

I came from 386.4 beta2, flashed 386.4 release, flashed latest stock to troubleshoot an issue with my node, reflashed 386.4. No issues with dhcp at any point.

 

[dominik]

Thanks for replies, I'll do that tonight and report if that fixes issues with DHCP.

 

[dominik]

Interestingly when I flashed Merlin yet again DHCP was working correctly, something have changed about entware (missing) and wireguard (previous tunnel not working). This makes me wonder if it's something about those two and not merlin itself. So I decided to clear settings and hard reset, then reimport my setup and check on each stage if DHCP has problem. I repeated all but now everything is OK.
Now I will use those for few days,
thanks

 

[L&LD]

Note that re-importing a saved backup config file negates the 'hard reset' you performed.

 

[dominik]

Note that re-importing a saved backup config file negates the 'hard reset' you performed.

That's why I asked if its possible to export only some settings and apply only those instead of rewriting everything.
Is there anything that allows to export settings from current page only? I need only few things like DHCP entries and ppp settings to quickly reconnect.

 

[pinkgrae]

Is there anything that allows to export settings from current page only? I need only few things like DHCP entries and ppp settings to quickly reconnect.

AFAIK only via a script. YazDHCP will allow you to save and restore your DHCP entries; not sure about anything for ppp settings - @Jack Yaz?

 

[Squall Leonhart]

Then I noticed that some devices are disconnected from network and they are not able to reconnect anymore. Checked few of them and quickly discoved that they autenticate but can't get IP or anything from DHCP server. On mobile phones it stuck at "obtaining ip address". With manual ip setup they were able to connect to wifi and Internet.

If coming from non-merlin firmware without a reset and you have multiple devices with some in a media bridge config, the media bridge will have its DHCP server turned on leading to some devices using the media bridge as the dns providing device even if they aren't connected through it.

http://<mediabridgeip>/Advanced_DHCP_Content.asp