Mine is not a bug, I am almost sure about it, but still;
Using Mi14, HyperOS2, latest stable.
VoWifi on SIM2 (KPN NL) works flawlessly, connects immediately, anywhere anytime, as usual.
But for SIM1 (VODAFONE TR) no way.
it was working last week, and this week I updated from HyperOS1 to 2
I am aware of the following, checked whatever I can read especially from
@gogocar62 and all other helpful people, with much thanks. The last resort would be the MBN settings maybe, but I am afraid of wiggling those scary gray 3-letter buttons without some help.
*#*#726633#*#*
- Enabled 5G SA Network option
*#*#34834#*#*
- Enabled Prefer 5G option in the Preferred Network Type if supported by your SIM Card (Carrier)
*#*#86583#*#*
- Enabled VoLTE (Voice Over LTE) option when 4G/LTE and 5G NSA/SA network (last digid says disabled)
*#*#869434#*#*
- Enabled VoWiFi (Voice Over WiFi) option when 4G/LTE and 5G NSA/SA network (last digid says disabled)
- Can see VoWiFi provisioned on *#*#4636#*#*
Talked to the carrier, disabled/re-enabled VoWifi services (4.5G, 5G, HD Voice etc)
Did full reset to connection settings, lost many wifi/bluetooth profiles, but was no big deal only if it helped...
The iphone device using same sim provider, can connect fine, changed the sims, and it doesnt connect when on my SIM1 or SIM2, also if I switch my simcards between SIM1 / SIM2, then KPN connects and my sim cannot. But My sim can connect when in iphone.
So after all these trials, then I thought it is beyond my knowledge. and here I am.
Edit: AI says iphone has single:multiple connections, but Xiaomi HyperOS has ephemeral port changes during handshake and Vodafone doesn't like that. But KPN is fine with it. So I did NAT-T on pfsense and tried fixing static ports too....and another long story with fw rules and etc. Finally now I m back to square1.