As you connect to your Gateway vServer using Microsoft Edge, ADC presents a popup windows to you: “Full VPN and EPA are not supported in Edge browser …”. In case you DO NOT use full VPN and / or EPA feature with your ADC / Gateway, you may get rid of those annoying message.
@jantytgat from corelayer.eu (@CoreLayerEU) published an article using a simple rewrite policy to remove that pop-up, see here: https://corelayer.atlassian.net/wiki/spaces/CSD/pages/19824657/Disable+Citrix+Gateway+pop-up+for+Microsoft+Edge.
Many thanks for sharing, Jan!