Will see when I get back to Sydney and buy a new package.

I spent most of last month in the US, I used an esim via the https://www.airalo.com/ app. Worked flawlessly. Useful for any longer travel situations.

Arrived back in a Sydney and mobile data still didn’t work so it wasn’t anything to do with being in Vanuatu. I managed to reach Skinny and apart from cycling phone on and off which hadn’t worked, they advised me to take the SIM card out for two minutes and put it back again.

Voila…it worked. Hope this helps anyone else with similar problem. 

This happened to me and also a friend i was travelling with who is also on skinny. Our other vodafone friends were not affected. 
Both had roaming packs bought and ready to go. 
Symptom: all websites blank 'hang', nothing loads. Also no functionality for other apps like maps, etc.  Identical to OP, 4g/5g showing, no pages loading. 

Steps tried (none of these worked):
* Rebooting phone
* Trying sim in multiple phones (old phone and new phone)
* Connecting manually to every Singapore telco we could see, singtel, yes, starhub, simba, etc
* swapping sim into vodafone friend's phone, fault moved with sim.

Also like OP, my APN settings only have an APN for "Personal hotspot". No other APN entries exist. (Is this normal??). "Reset settings" did nothing. Cannot add apn manually.

After being on hold for an hour then spending a fruitless 45 minutes with skinny phone support (who did not know what an APN was and "wasn't allowed" to escalate to any kind of tier2 or network support) we gave up on skinny completely and purchased singtel eSIMs.

Also i tried all this again in malaysia, where skinny mobile roaming also failed. Same symptoms. 

After returning to NZ i have been looking into the APN thing further. Still no mobile data APN (not that that matters for home presumably as mobile data is working here).

Today i upgraded from my old sim to a skinny eSIM. Still no mobile data APN entry, even after trying Reset Settings many times. 

Question: is it normal for there not to be a mobile data APN on skinny?
Question: if not, is the lack of the APN related to mobile data roaming being broken for me?

Question: How can i get skinny to fix this if i want to keep being a skinny customer, short of porting out to somewhere else then porting back in to skinny as a new account?

I'm currently over in Singapore and experiencing some of the same issues as the OP

Singtel - I get VoLTE with working calls and TXTs if I select 4G or 5G on my Android phone, but mobile data won't work

Starhub - takes a couple of attempts before I can force a connection, but I can then get working data.

Try turning on a VPN (preferably one you control both ends of, not some sketchy app-store vpn)

I've been to more than 1 country where roaming doesn't work properly due to MTU issues, tunneling packets via a VPN works though.  Won't think this was a problem in 2025 tho.