I had problems with xiaomi.eu rom: could not choose sim ( dual ) by texting and problems with volte.
Now i have global rom 12.0.1 and everything works.
https://www.giztop.com/xiaomi-mi-11-5g.html :
COMPATIBLE WITH ASIA / EUROPE / AUSTRALIA BANDS
5G: Sub6G: n1/n3/n28a/n41/n77/n78/n79
4G: FDD-LTE: B1/B2/B3/B4/B5/B7/B8/B12/B17/B18/B19/B20/B26/B28A