I used to have a single cable in my wall for the "old astro" then later switched to Astro IPTV, the installer didn't setup the dish for me.

Does this means new decoder can use back the single old cable without need to hacking the wall for 2nd cable?

If you're trying to replacing to your own third party router (e.g. Asus), you're still able to watch/receive Astro IPTV service with your Asus router.
Not necessary only Maxis routers can watch/receive Astro IPTV service one. Just make sure your router's VLAN (a.k.a VLAN Tagging) settings is configured to Astro IPTV's VLAN settings for the particular LAN port that you're about to connect to your Astro box. But usually, it has been pre-configured by default (provided you bought the router in Malaysia).

By standard installation, Astro's IPTV function will only work via Ethernet LAN cable connection, similar like Unifi TV on TM Unifi Fibre network.
Astro's IPTV won't work via WiFi connection directly from Astro box to your router. (Accessing to VOD content not counted la). 
Why? Did you face any trouble connecting your Astro box to your router?

If your house/area is under TM HSBB network, you can switch from IP mode to Satellite mode whenever the Astro box detects that "network is down" and unable to receive any channels via IP mode.
They call it Hybrid mode.

But if your house/area is under Maxis NGBB (Maxis's own fibre network, not share with TM) or TIME Fibre network, then bye bye.
Your Astro box is solely dependant on network (IP mode) and you cannot switch to Satellite mode even if you connect your Astro box to the satellite dish. Basically, Hybrid mode is disabled for you.

Err I'm kinda confused..

Are you using IPTV, or just the normal HD box? If it's HD box, both WiFi and IPTV function will not be available.
Only PVR box can be used for Astro IPTV. And usually if you're using Astro IPTV, it is connected via LAN cable, therefore WiFi may be disabled by the software.

If your subscription has HD-PVR service, either by adding RM26.50/month or subscribed to either Value Pack/Super Pack/Super Pack Plus or Family Starter, you are eligible to HD-PVR service.
You can upgrade to PVR box without any additional monthly fee. But a one time installation fee may be imposed depending on any ongoing promotions or subscription. Double confirm with Astro if you want to know more. And once you change to PVR box, 24 months contract will restart.

Can you share with us the Asus router model number, so that can check whether your router can support VLAN configurations or not. Cuz usually router nowadays can support VLAN.

If you're confident that your area is under Maxis network (not TM), then hybrid mode are not available for you.

the "Cloud record" on Go app one.

"Upgrade Astro Cloud"... sound like they'll charge for storage.

How many of you that use the recording function? For me, I rarely/never use it before...

because astro refuse to code those channels in MPEG4, instead still stuck on MPEG2.

Depends on the provider. Likely when showing F1 it will show Fox Sports logo. In any case, they just bundle every 4K broadcast under the Astro UHD banner
DTV is encoded straight from the source by the broadcasters themselves, be it RTM or Media Prima. For SD on Astro meanwhile, they usually take the broadcast, and re-encode them with a lower bitrate and resolution. IIRC astro's SD channel are slightly above 360p only in terms of resolution, which is why it looks so shitty compared to DTV which are usually 480p

Astro has removed the letterbox on almost all of its SD channels for quite some time already. The SD channels itself is technically still in 4:3, but they make it fit to screen so that letterbox won't be shown.
And yes, Astro still uses MPEG2 4:3 for its SD channels so that legacy Astro boxes can still be used, which supports only the older DVB-S standard and MPEG2 video codec. Previously there are complaints from some legacy STB users whereby if the SD channel video itself is in native 16:9 aspect ratio, it will display only a black screen and audio only. Presumably is due to compatibility issue on the legacy boxes as it "doesn't recognise" or "don't support" 16:9 video. So they got to transmit it in 4:3 from their side, but remove the letterbox so that no black bars will be shown.

Meanwhile, there are still a handful SD channels on Astro that still did not remove the letterbox, such as TVB Entertainment (ch313), all Astro AOD (SD) channels, Asian Action Channel (ch327) and TVB Classic Movies (ch328), CNN (ch511), and others.

However, all Astro AOD (SD) channels, Asian Action Channel (ch327) and TVB Classic Movies (ch328) are found to be the only SD channels on Astro that uses MPEG4 video codec with HE-AAC audio codec. These channels does not appear on the channel list for legacy Astro boxes.

For now, any cloud recordings made on Astro Go app are only viewable in Astro Go, and you're not able to watch it on your PVR box.

only those subcribe to HD services can view them.
astro not doing social services but business entities 

They've been planning to migrate all legacy box users to newer platform since many years ago. But they're simply not aggressive enough to convince or force legacy box users to use the new box. Even if the customer are being stubborn and reluctant to swap to the newer box, Astro should just discontinue it by force, transmit all SD channels in MPEG4 and in DVB-S2, and legacy box users won't be able to receive any signals anymore, making it no choice but to swap to the HD box to continue watching Astro.

It's been years that HD service fee (RM25) is no longer compulsory to subscribe if swap to the HD box. Although Astro sales agent will convince you to subscribe, that doesn't mean you have to subscribe mah... Their monthly subscription can still be remain the same as now if they aren't interested in HD. So why they're reluctant to upgrade? I don't get it leh...

There are some package offerings that is only available on B.yond platform, such as Korean Pack, Sports Focus pack, and others. And also some HD-only channels like Boo, tvN Movies, BeIn Sports, and more. This is also to encourage users to use HD box as well.

Seriously it's time for them to move on, and decommission the use of all legacy box models for good.

...and only landed houses for now.
Even for those who stay in MDUs (high rise buildings), doesn't matter using own individual dish or centralised dish, also cannot.

Do take note of these:
1) You should/must tell them that you're using a UHD TV, or else they won't give you access to "Astro UHD" channel on CH780.
Meaning if you go to that channel, it'll show "Subscription Required" even you're using Ultrabox. And nope, they're not gonna let you watch the downscale version of UHD quality channels to 1080p for you.
2) Must be connected to an Internet connection of 10Mbps and above to access to cloud recording feature and access to On Demand library.
There's no hard disk included in the Ultra box. They don't plan to allow users to connect external hard disk to do recordings, for now (cuz Ultra Box has one USB 3.0 port).

As for satellite dish, the LNB will change to DCSS type.

And here's the installation fee charges, which I've confirmed with Astro:

Monthly subscription rate	Installation Fee	24 months contract
>RM100 (excl. SST)	Free	Yes
<RM99.99 (excl. SST)	RM199	Yes
Doesn't matter	RM499	No contract

Cancel within contract period? RM1600 penalty charge.
*The monthly subscription rate shown above is apply as per primary subscription.
For instance, if you pay RM100 and above (excluding the RM50 per Multiroom subscription), then you're eligible for free installation.

Err basically yes. Contact Astro to fix an appointment date for the installation. Although they haven't publicly launch yet, but they seems to accept upgrade applications now.

Hmm, I'm not sure about this. But better just let them know that you're already using 4K UHD TV so that you'll guarantee able to have access to UHD channels (provided the particular channel is not pay per view or require additional separate subscription). Yeah, lie to them 😈 Muahahaha...

But of cos, if watch UHD channels on a Full HD TV, later don't say "I don't see any difference compared to HD and UHD channels". I think that's the reason why Astro want to make sure of that. They wanna make sure only customers with UHD TV can access to UHD quality channels.

And tell them in advance that you have Internet of 10Mbps and above at home cuz they'll always remind you this.

For Astro IPTV I'm not sure... Need to check with Astro.
Maybe it's available to upgrade for Astro DTH customers only for now.

What I know is, almost all can record now, including RTM and Media Prima channels. Except Astro UHD channel 780, where Record button doesn't appear on that channel.

Try power off then power on the Ultra Box again.
If you're very sure that it can't be connected even with the correct password, try connecting to other WiFi network. Example if your router is dual band type (2.4GHz and 5GHz), try connect any one of it.
If still can't, try temporarily turn on WiFi hotspot on your phone for your Astro Ultra Box to connect it, see if it can connect successfully or not, then you'll know where the problem comes from.

Oh? HDCP 2.2? Hmmm... Okay then.
At least Astro can no longer use the same tactic as what they've been doing for the past 10 years; additional monthly HD service fee like +RM20-25/month.
They can't just convince all customers to buy new UHD TV