Problem sharing internet via WiFi Hotspot (tethering) while in foreign country roaming

I noticed, whenever I am in foreign country (i.e. DATA ROAMING) I can connect other devices to my android phones via its hotspot, but they (devices) have restricted access to internet.. In other words: My phone, where I would like to share internet via operator's data in foreing country roaming DOES have internet access, but devices connected to it via WiFi hot spot do NOT. As soon as I return to home country, the problem disapears and tethering works normally. This I've noticed on 2 Android phones I owned and tried: Nokia 6.1 and Motorola G10. Vendors claim they do not have a fix for it, operator also claims he is innocent. Does it look more like a problem of Andorid OS, foreign operators, or my home operator ? **Edit:** (based on Robert's suggestion) **My home country:** Slovakia (Not to be confused with Slovenia) **My home operator:** 4ka **Foreing countries traveled:** Austria, Czech Republic, Germany, Netherland, Belgium, France, Luxemburg **Foreign operators:** Any one I encountered. Really do not know their names. Can anyone help to identify the source of the problem, please ?