-snip-
Just like my guess.
So, most of the time is because of the restricted country of the provider. In some casino sometimes only show ERROR, and meanwhile some casino can give user a notification the country/IP are being restricted due the term & condition from provider.
In these case, some casino allowed user using VPN to bypass only provider restricted. However, you can double check and ask with betpanda support (can we bypass these with VPN or not).
error messages can eminate from various factors and notably the ones you mentioned could actually be the reason while some players recieve error message while trying to load the casino site, but then also we have not mentioned one other factor which is the use of VPN to access the casino.
Because some gamblers from restricted jurisdiction may optin to using vpn to access the site which ultimately have to demand for high data consumption and if the traffic is a kind of busy, VPN users are the first hit internet users and sometimes error messages become the response their get from the site, but other gamblers who may not be using VPN in same location may not receive such an error message and can play on the site freely.