Asus RT-BE88U (Merlin WRT) suddenly does not seem to connect to LAN over OpenVPN config
I have Asus routers for many years already, and I love the Merlin WRT firmware while it always was very stable (modified stock firmware if I'm correct) and easy to integrate in automatization instances.
While having a lot going on at home because of having quite a few things running in automatization and servers, it's pretty handy/ useful being able to reach the LAN-network, even when being away from home.
So I always configured the OpenVPN option inside the Asus routers/ Merlin WRT firmware.
Never had problems with it and it always worked flawlessly over the OpenVPN app on other devices like phones or laptops.
Having a RT-BE88U now for some time, which worked flawlessly for quite some time.
Since one of the last updates (started from around oktober 2025 if I'm correct), OpenVPN seemed to got "broken".
Being able to get on the same IP when being outside the LAN-network, so it makes connection through the router. It also shows connected with the current WAN-IP from that device, but somehow I can't reach LAN (like Servers/ NAS/ Router) anymore. And while having "Client will use VPN to access" set to "Both" (both LAN & internet).
I first thought it was an update issue, while it seemed to have started immediately after a previous update. So I waited a few updates hoping this would fix the issue after not getting it solved.
A few updates had passed, which did not solved the issue though. While I use Technitium DHCP for quite a bit now, which took over the internal DHCP routing of the router, I also tried to eliminate this possibility by turning off the entire server. Even started from scratch after that by putting the router back to factory settings. To be clear, OpenVPN and LAN acces functioned before in these settings.
This is wat I tried so far again:
Preparation/ configuration:
- Proxmox / Technitium DNS shut down
- RT-BE88U DHCP-server turned on
- VPN server 1 cofigured & enabled
- "Client will use VPN to access" on "both"
- Exported OpenVPN configuration file configured on telephone
Testing on same LAN:
- LAN devices (so also phone) show same WAN IP 82.**.***.***
- NAS and router are reacheable ffom other network devices from local (static) IP (aslo from phone)
Testing outside LAN (step 1):
- WIFI on phone turned off
- Phone isn't in LAN anymore now and shows other IP (83.***.***.** instead of 82.**.***.***)
- NAS and router are not reacheable from local (static) IP anymore from Phone (which is correct)
Testing outside LAN (step 2):
- VPN - Status on RT-BE88U doesn't show connected devices
- OpenVPN configuration file on OpenVPN app on mobile activated, shows connected
- VPN - Status on RT-BE88U now shows the connected phone from IP 83.***.***.**, so OpenVPN coonection seems established
- NAS and router in LAN are still not reacheable from phone with established OPenVPN connection.
So after trying quite some things after this today, I'm quite out of ideas now. Anny idea how get this working again?
I have Asus routers for many years already, and I love the Merlin WRT firmware while it always was very stable (modified stock firmware if I'm correct) and easy to integrate in automatization instances.
While having a lot going on at home because of having quite a few things running in automatization and servers, it's pretty handy/ useful being able to reach the LAN-network, even when being away from home.
So I always configured the OpenVPN option inside the Asus routers/ Merlin WRT firmware.
Never had problems with it and it always worked flawlessly over the OpenVPN app on other devices like phones or laptops.
Having a RT-BE88U now for some time, which worked flawlessly for quite some time.
Since one of the last updates (started from around oktober 2025 if I'm correct), OpenVPN seemed to got "broken".
Being able to get on the same IP when being outside the LAN-network, so it makes connection through the router. It also shows connected with the current WAN-IP from that device, but somehow I can't reach LAN (like Servers/ NAS/ Router) anymore. And while having "Client will use VPN to access" set to "Both" (both LAN & internet).
I first thought it was an update issue, while it seemed to have started immediately after a previous update. So I waited a few updates hoping this would fix the issue after not getting it solved.
A few updates had passed, which did not solved the issue though. While I use Technitium DHCP for quite a bit now, which took over the internal DHCP routing of the router, I also tried to eliminate this possibility by turning off the entire server. Even started from scratch after that by putting the router back to factory settings. To be clear, OpenVPN and LAN acces functioned before in these settings.
This is wat I tried so far again:
Preparation/ configuration:
- Proxmox / Technitium DNS shut down
- RT-BE88U DHCP-server turned on
- VPN server 1 cofigured & enabled
- "Client will use VPN to access" on "both"
- Exported OpenVPN configuration file configured on telephone
Testing on same LAN:
- LAN devices (so also phone) show same WAN IP 82.**.***.***
- NAS and router are reacheable ffom other network devices from local (static) IP (aslo from phone)
Testing outside LAN (step 1):
- WIFI on phone turned off
- Phone isn't in LAN anymore now and shows other IP (83.***.***.** instead of 82.**.***.***)
- NAS and router are not reacheable from local (static) IP anymore from Phone (which is correct)
Testing outside LAN (step 2):
- VPN - Status on RT-BE88U doesn't show connected devices
- OpenVPN configuration file on OpenVPN app on mobile activated, shows connected
- VPN - Status on RT-BE88U now shows the connected phone from IP 83.***.***.**, so OpenVPN coonection seems established
- NAS and router in LAN are still not reacheable from phone with established OPenVPN connection.
So after trying quite some things after this today, I'm quite out of ideas now. Anny idea how get this working again?
