Emm the evening i try to connect Ether 4 with GN630V,and also occurs disconnection within 10mins.
And before that i was testing with tplink router.
So i just make assumption that my RB5009 Ethernet is broken. Since the internet just randomly disconnected with Ether 1 2 4.
Before i wake up it didn't have disconnection issue,but the problem just occurs after 11am or 12pm.
And after 4pm it keeps dc me from unifi every 5-10mins. very random. And no ether down log at all.
Although i did see a few 2.5G ether down log from GN630V log.

So currently my final thought is RB5009 is broken in someway,but i could not said the accurate root cause.
I would try to connect RB5009 tomorrow as last try to see any chance that normal again.
But i dont think so,since 1 tplink plus 1 hEX can work without any issue,then it is very highly chance that issue is on RB5009.

Not necessary. The bug could only show up when negotiating 2.5G speed.
That's why I recommend configuring your rb5009 to not advertise that speed when you test it again.

BTW, did you get latency spike when doing upload and torrent using HEX (without Queue)?

The RB5009 only have Ether1 as 2.5G port,others is 1G port.
Which mean it will nego as 1G to work with GN630V.

Make sense!
Try without the UPS + original power brick then. If still drop, buy a new one with L3HW Offload.

Thats why i said RB5009 might be broken. 
Which mikrotik model u recommended. Must be powerful than RB5009 but prefer home usage ..haha
I use alot of wireguard tunnel,so cpu better will be useful for me.

Too many core also not useful for home usage.

Oh man... You definitely do not want to ask me that question as I am not qualified.
As of now I like their CRS520-4XS-16XQ-RM. 100gig baby!

But they are gonna launch some new product with Ampere high core count CPU, sure as hell won't be cheap and they will most likely be 100gig or more as well.

For home use, nothing beats 5009. But then RouterOS do not use any of the HW Offload for this SoC as it is too limited. Plus the packet buffer is also very shallow. It is okay for home use.

VPN wise, I don't do them on router. Do it on a PC with AES-NI.

Anything with fan will have noise yea. So consider that too.

Which model is the upper level of RB5009.
I am going get that one.
But the sadness is i also need to get a separate UPS for it. 

I consider CCR2004-1G-12S+2XS to be one step above 5009. It is fanless too.
But since it is all SPF+/28 port, you need to buy a module to do RJ45 (GTek score very high in Serve The Home test)

-OR-

Do Router on a stick setup (ROAS) with your switch (if it support VLAN)

Emm not suitable for home usage.
Price abit high.
I was thinking to get something lower grade like hAX3（similar cpu grade） to wait for new successor and buy.
Since i can cope with this hEX for abit more,but this is temporary,as i already promise my cousin that i will give them the hEX for their home network. (And this is abit old cpu,not enough for me to use for daily usage)

Currently didn't have plan for custom diy router. and no vlan switch used.

Sorry, that model has fan with a huge heatsink. I missed it for another older pure fanless model which is no longer listed.

AX3 works too. Just that it only have a single 2.5gig port. So all your device is going to have 1gig max but they can all share 2.5gig to ONU. You do get wifi with it although it only support 80MHz max instead of 160MHz.

However, you can still do ROAS setup with the AX3 if your switch can do VLAN. Then all your device can get at least half duplex 2.5gig. Still a win!

Shit i forgot i need the SFP+ for the 2.5G switch,as i already didn't have enough ethernet port... 
Maybe a second ethernet only switch is better choice? (Or second 2.5G Switch  )
I only need abit more port for low bandwidth device like CCTV NVR,RPi, Zigbee hub,and 2 AP...
2.5G is reserved for PC and NAS...

Ah wait only 1 2.5G port mean i can only choose either WAN or LAN...

Erm... Those can be done but they involves buying even more stuff which sort of defeat the purpose?
By the time maybe you are looking at 10gig upgrade.
Maybe just buy another 5009? The one with all port PoE and just call it an upgrade?

Emm it might really be the choice...and the simplest way to solve my problem...
But i didn't use PoE...any improvement beside the PoE? Or switch chip better?

Nope. There is nothing to improve in the 5009. They already maximized the SoC. If you read the SoC datasheet, Mikrotik has absolutely connected everything they can to it already.
So just get another 5009 then.

The rest of the router family don't have 2.5gig + SFP+ port either.
Those switching family don't have powerful enough CPU.

Okay Thanks.
Let me test tomorrow for the final chance or life for RB5009.
If still not okay,then i will contact Subtel to see possible to repair or not.
If not then i might get a new one... 

Just a suggestion. Whenever it dc, generate a supout file and send to Mikrotik.
Who knows it is a firmware issue with the switch chip.
Mention that the ONU detected the port flapping.

You save yourself a lot of agony buying another 5009 with the same bug.

But er... If it is happening with your old ONU too, I say don't put a high hope.

95% of disconnection didn't have any ether down log ,just dc with no symptom. 

Slowly think about it yea. I understand the feeling of buying the exact same model number as a replacement don't give you excitement.

Maybe buy a HEX Refresh and do 1gig till Ampere comes.
Trust me you are not really missing much on that last 100meg of bandwidth.

hAX cpu better right?

Yes it is. Just different price point. If you don't need the wifi then you are paying double the money just to get the last 100meg. Even that cannot be used directly on a single stream.

There is no right and wrong way of going about it.

Either you go for maximum economy, and only upgrade when TM gives another FSU.
or
Purchase the exact same hardware as direct replacement
or
"Upgrade" now. The word "upgrade" is subjective. If you need wifi, AX3 is an upgrade. If not, then i don't really consider it a worthy upgrade.

You might very well need an upgrade anyway for next FSU if TM change to XGPON or 50G-PON. They might need 10gig RJ45 or they go straight to SFP+ port. Only time will tell.