E5783b-230 MiFi no 5GHz WiFi when roaming

I hope someone can explain this to me:

I bought the E5783b-230 for it's dual band (2.4 and 5GHz) capability. I used it in France with a French SIM and only got the 5GHz WiFi to work when allowing 4G networks. Took me a day to find out that setting. Now I'm back in the Netherlands still using the French SIM only to find out that the 5GHz band doesn't work. On the settings page on a computer it simply says 5GHz is not available on the basic page and on the advanced settings it says that you shlould enable it on the basic page (settings). In the AI app it states that "5GHz is not available when roaming internationally". Why is that? I bought the router (and it is a router right?) for it's higher speeds, also between devices connected. I would expect the 5GHz to work even without a SIM in place, just to create a local high speed network. I tested it with a local (Dutch) SIM and then 5GHz is available. Why not when roaming? It seems silly restriction, I know exactly what my data use is. Why is this restriction there? I think it can easily be solved by changing some code and put out a firmware update. Please resolve this, I think about returning the device because the 5GHz band (when routing) was the reason for buying it in the first place.