Hi,
Can someone advice me what should I check and advise me why my home WIFI lost connection whenever hAP ac³ powered up?
I tried to setup my lab environment, and regardless which ports connected (wireless interface disabled), my mobiles will experienced lost WIFI connection, but once power it off, the WIFI resumed.
Tried factory reset few times, but the problem still.
Please advice how to troubleshoot my problem.
Regards,
Johnson
I can't find any useful details that could provide even the slightest clue.
When you plug the hAP ac³ power supply into the power outlet,
do you unplug the power supply of the other one generic, unnamed device?
Are you behind an ISP router?
Are you behind an ISP supplied router?
No problem. You can go on a forum and you ask people for their help. Don't forget to include all the relevant information which you know and which you cannot expect them to know.
In general when troubleshooting, having a diagram of how things are connected is very useful. It can provide you with a "map" of where to look for the problem.
Your problem description is too vaugue to be helpful for anyone to troubleshoot remotely. All you will get are "guesses".
Given
and nothing else, including any "time" till problem seen, or problem resolved, my "guess" would be that this may be that you have connected the LAN side of the hAP ac³ to the LAN of your isp router, and the hAP ac³ has its DHCP server enabled, but it has no internet access.
Can you provide a network diagram (even a photo of a hand sketch is much better than words alone).
Also, a better description of what you mean by "my home WIFI lost connection". Because you stated "wireless interface disabled", so it seems unlikely that your mobile devices are "connecting" to the wifi on the hAP ac³. But if the hAP ac³ has connected a dhcp server to your "LAN", then it may be providing ip configuration for the mobile devices, and setting their default gateway to the ip address of the hAP ac³'s bridge interface.
But I wouln't expect that to affect active connections. It would only affect what ip settings are obtained when a roaming device connects to the existing wifi and sends a dhcp request for a previous ip address it had a lease for on another network and receives a DHCP NAK for wrong network. This will cause the mobile device to start fresh with a dhcp discover, and then the mobile device may choose the offer given by the hAP ac³, along with its bridge address as the default gateway to use.
Then your mobile devices won't work if the hAP ac³ itself has no internet access. But it probably won't attempt obtaining new ip information until its lease expires. This makes the second symptom "but once power it off, the WIFI resumed." not likely to happen "immediately", but only after any dhcp lease it currently has expires, or wifi connection is lost.
But withour a lot more details than you have provided are supplied, all you will get are just SWAG.
Start with the basics: Google network troubleshooting
Here's a useful flowchart but may be less useful if you already know what causes things to stop working.
FLINT HILLS TECHNICAL COLLEGE Network Troubleshooting Flowchart
What ip address is the hAP ac³ using? Another possibility is that you have two Mikrotik devices both using 192.168.88.1/24 as there LAN ip address, and you connected the two LANs together. That will have a less delayed affect than a "rogue dhcp" server described above.
This is where we need more details than you have provided.
When the hAP ac³ is powered off, what ip addresses do your wireless clients obtain, and what is their default gateway set to?
What changes on the mobile devices when the hAP ac³ is powered on. How long does it take for the problem to show up? How long does it take to start working again after the hAP ac³ is powered off?
This is currently the best guess, based on the description provided... 
This usually points to an IP or network conflict rather than WiFi itself.
Check if the hAP ac³ is using the same IP range or running DHCP on the same network as your home router.
Even with wireless disabled, a conflicting DHCP server or bridge loop can break connectivity.
Try connecting it with only one Ethernet port and make sure DHCP is fully disabled on it while testing.
Once there are no IP or DHCP overlaps, the issue normally goes away.
Even if there's an IP address conflict, the WiFi disappearing and devices disconnecting doesn't add up.
The user's description could also be incorrect.
An incorrect description leads to incorrect assumptions