Hello everyone,
I’ve been working for a couple of days on configuring a failover setup on a MikroTik router to maintain internet connectivity via LTE when the fiber connection goes down.
Main issue
The failover itself works correctly, but I have a major problem:
I am NOT receiving notifications on my mobile device when switching between Fiber and 4G (failover), especially when the phone is connected via WiFi.
Observed behavior:
-
If the phone is on WiFi:
- Notifications stop arriving after the failover.
- They only resume if I manually change the connection (e.g., switching to mobile data).
-
If the phone is on mobile data (4G/5G):
- Everything works correctly, no issues.
-
Additionally:
- Home Assistant Cloud takes some time to reconnect (I partially mitigated this by restarting it via webhook).
This leads me to believe the issue is related to persistent connections/sockets that become invalid after the public IP changes.
Context
Initially, I also had issues with Home Assistant Cloud after failover, but I solved that by sending a webhook to Home Assistant to force a cloud reconnection.
However, the notification issue still persists, which is my main concern right now.
Current network topology
- ISP router (fiber)
- MikroTik (handling 4G failover)
- TP-Link Deco Mesh (in router mode)
I know this is not ideal. My future plan is:
- ONT + MikroTik as the main router
- Deco in AP mode
But for now, I prefer not to change this until everything is stable.
Failover behavior
- WAN (fiber) → distance 1
- LTE (4G) → distance 2
The failover works correctly:
- Automatic
- Fast
- No noticeable interruptions
The issue is not the failover itself, but what happens afterward.
Technical issue observed
When switching between Fiber and 4G:
- The public IP changes
- Some connections remain open or become invalid
This results in:
- Notifications not being received over WiFi
- Temporary issues with Home Assistant Cloud
- Affects both cloud access and local access (I use Tailscale)
MikroTik script
I use the following script to detect the change and trigger actions:
:global lastState
:local haIP "IP_HOME_ASSISTANT"
:local activeRoutes [/ip route find where dst-address="0.0.0.0/0" active=yes]
:local bestDist 999
:foreach i in=$activeRoutes do={
:local d [/ip route get $i distance]
:if ($d < $bestDist) do={
:set bestDist $d
}
}
:log info "[CHECK] Active distance: $bestDist | Previous state: $lastState"
:if ($bestDist = 1) do={
:if ($lastState != "WAN") do={
:log warning "[FAILOVER] >>> SWITCH to FIBER (distance=$bestDist)"
/tool fetch url="http://$haIP:8123/api/webhook/failover_fiber" http-method=post keep-result=no
:set lastState "WAN"
:delay 5s
/ip firewall connection remove [find protocol=tcp dst-address=$haIP dst-port=8123]
/ip firewall connection remove [find protocol=tcp src-address=$haIP src-port=8123]
/ip firewall connection remove [find dst-address-type=!local]
/ip dns cache flush
}
} else={
:if ($lastState != "4G") do={
:log warning "[FAILOVER] >>> SWITCH to 4G (distance=$bestDist)"
/tool fetch url="http://$haIP:8123/api/webhook/failover_4g" http-method=post keep-result=no
:set lastState "4G"
:delay 5s
/ip firewall connection remove [find protocol=tcp dst-address=$haIP dst-port=8123]
/ip firewall connection remove [find protocol=tcp src-address=$haIP src-port=8123]
/ip firewall connection remove [find dst-address-type=!local]
/ip dns cache flush
}
}
Home Assistant automation
When the webhook is received:
- It restarts Home Assistant Cloud
- Sends a critical notification to the mobile device
Questions
I would like to understand:
- Am I handling connection tracking correctly?
- Is removing connections this way the right approach?
- Is there a better way to prevent persistent connections from breaking after an IP change?
- How is this typically handled in failover setups with services like Home Assistant?
Any help or guidance would be greatly appreciated.
Right now, failover works perfectly, but notifications are no longer reliable, which is exactly what I need to fix.
Thank you in advance! 