As an operator, you cannot rely solely on the manufacturer's statements. Here you can find out why this is the case and what options there are to mitigate this.
"... In a presentation at last year's 34c3, the 34th Chaos Communication Congress, Thomas Roth gave an impressive demonstration of the security situation of some industrial routers. Industrial routers are used in almost every automation network.They are the connecting links in the automation network and play an important role in the functional maintenance and safeguarding of these networks. ..." - www.sichere-industrie.de