Got, TIME Fibre is using those.

But if you're interested in replacing your current setup to a 2in1 I think most ISP's can't and won't help you

for a typical installation you will get 2 items

the Modem/ONT, which is ISP property and you must return it to the ISP after you end your subscription
Most people never touch this and just use it as is and is good enough for most people
This is where the fibre cable connects to

then, a router is provided which plugs into the ONT via Ethernet, this one is your's to keep after the 2 year contract for most isps
most people replace this with their own as the isp provided one isnt great

some isps like TIME to save cost/save space/save power provide an all in one solution, 1 box, directly connects to fibre

This thread is for enterprise tier where you can plug fibre directly into a sfp module on your own custom router setup

For your use case, I'll recommend you just stay with having 2 items

This thread is an example of "If you don't know anything even in layman terms, you probably don't need it."
So far almost all ISP provides you with 2 devices by default, ONT/ONU box to terminate your fibre into a signal your router can understand, and the router for the actual PPPoE, AP, etc etc. I have seen AIO boxes that has the fibre directly connected into the router itself but those are rare and replacing those are super hard. But if your ISP provides you with two boxes, you can just swap the router given to you out quite easily.

Most people here wants to ditch ONU boxes due to the extra plug that it takes up hence extra power consumption, also you can assume if you're investing upwards of 1k in network gear, you'll most definitely have a UPS. And with UPS comes limited power plug and limited battery capacity to keep their internet up and running even in an event of blackout. 

Hope this clarifies why people are doing it this way and why you probably again, don't need to do any of this. 

not sure if TM will let you keep streamyx as you're basically upgrading to fibre from copper in their system
(unless you mean upgrading 1 of the 2 streamyx to fibre and keeping the other as streamyx)

in terms of decreasing devices, the ont isnt too big depending on the model you get, some people stack the router on top, might affect thermals but should be fine if you add a cooling fan

sadly I don't think there's really much choice for you

going with enterprise tier (sfp module, sfp router) is going to be very expensive + need to know how to setup as tm probably wont help you
consumer tier ones like the all in one boxes that time fibre uses, not sure where to get them and again not sure if tm will help you setup

I don't exactly understand how your config is working currently but here's my parent's old house procedure. TM upgraded infra around that area, we went from Streamyx 8mbps to Unifi 30mbps fibre, FOC and with discount iirc, and is currently paying 60-70ish RM per month for it. They let us keep the old Archer C5v, but pulled new fiber from our backyard to in house, both of the ONU/router are both FiberHome. And with how TM is trying to transition away from copper, I doubt they'll let you "keep" the Streamyx ADSL connection. Our old phone line that's used for ADSL is left as is and not touched since then.

And for your usage, the best I can recommend is the TP-LINK XDR5480, a TP-Link router from China that has been proven to work with SFP ONU xPON stick here and is probably the best use case for what you're trying to do. For your 4G whatever, I assume it's either a 4G dongle or Unifi mobile? No offense but your wording is all over the place so I can only assume it's a 4G dongle? For that you're probably gonna have to just trial and error with, Anime4000 here has succeeded in putting their dongle as 4G backup in case of Unifi side failure but it's really complicated for a beginner.

Or... the other option is get a Mikrotik hEX S/hEX POE, repurpose your old router as pure AP and off you go. There's not that much options that's somewhat cheap-ish that is an AIO(ONU + Router + AP, that's not pure e-waste anyway).

Side-note the XDR5480 is about RM550 on AliExpress atm.

I don't see why TM would let people keep original phone line where it's more susceptible to copper damages, pretty sure all Fiber connection has a phone line that's based on a seperate VLAN, VLAN400 iirc, Unless it's not covered by Unifi, then they'll do it. Even if not covered by Unifi, currently Allo is working extra hard to cover areas not covered by Unifi. Unless you live somewhere REALLY remote, you'll most likely get Unifi and Streamyx will be deprecated/legacy for your area. If I'm not wrong people that's still on Streamyx will be forced to upgrade to Unifi if the infrastructure is available at their area. That's what happened to my parent's old house anyway, they just send a message informing they'll be performing an upgrade from Streamyx to Unifi.

For your huawei 4G modem, what purpose is it serving? Backup? Fallover? As I don't see why not just get a smaller dongle/router that has only a single LAN, or better even, consult Anime4000's setup for their 4G dongle in router as failover, saving another plug and space.

And yes that's the SFP port you'll need to plug in SFP ONU xPON.

Then I'd recommend you look into using your 4G as failover with Anime4000's setup as reference. If your package is the default 30mbps then you can probably consider to keep 4G as main? But if it's 100/300, just ditch the 4G modem, put the SIM into a dongle, use it as a backup and change to Unifi as your main. Or if you really have the budget to spare, consider going 800/200 and use SFP ONU xPON to maybe bypass hard cap of TM OLT to reach higher speeds, Anime4000 has managed to surpass 200mbps upload provided by TM and get about 500mbps upload, way beyond what TM offers as part of their package.

This has been done by lwk523
ISP: Umobile
Fiber: Allo



NOTE:
He tested via Wi-Fi 6 2x2, download speed should be more than 1.3Gbps like izhamsatria did with Unifi with 10Gb Switch:

This what I did for having telephone line
https://forum.lowyat.net/topic/5243640

Fiber still direct to Router, map VoIP VLAN to any LAN Port, and use IP Phone with screen!

You can use ATA device (Analogue Telephone Adapter)

well then, I better you stick with stock ONU

what ISP are you using? XDR5840 not support VLAN Internet, only VLAN IPTV, I have tried it even UI in Chinese only

I can source that device for you and let Anime4000 to guide on configuration

do you want to keep VoIP ?

If you want SFP router with RJ11/VoIP... I don't think has one,
You need use VoIP Telephone (IP Phone) like Yealink VoIP

sorry out of topic, which telco and package u using for this 4g internet? and do u have any good 4g wifi router to recommend?

since this 2.5GbE, yea,

it should be support all plan since ONR no longer life time warranty 😅

adding ATA Chip is another cost, sadly I only manage to do this for now

sure thing 😬
can support, untag vlan500 + tagged vlan400 at one port
Yes, no POTS 😞

Any "mini" ATA adapter compatible with your ONT with unifi voice?
If unifi POTS works,i will get one set from you in near future. (Haven't received unifi FSU,still waiting for the new ONU changes for unifi in order to ask for FSU)