no internet connection with Telia dongle at Denmark

[so32foot]

With a Telia dongle I had excellent internet connections during my trips at the east coast of Sweden and Turku. However, at Denmark I often had no connection, especially around the Little Belt. Both at anchor places or harbours. Telia Denmark told me that this could be related to too much traffic at times. Mostly the signal indicator showed enough strength.

Is there a better network for sailors at Denmark available?