To turn on Internet Explorer mode, use the following steps. In the address bar for Microsoft Edge, type edge://settings/defaultbrowser and then click Enter. Slide the Allow sites to be reloaded in Internet Explorer toggle to ON. Restart Microsoft Edge. Internet Explorer mode is now enabled.

Switch back to classic Teams. The new Teams has full feature parity for almost all features including custom line-of-business apps, third-party apps, breakout rooms, 7x7 video, call queues, PSTN calling, contextual search in chats and channels, cross-post a channel conversation, and more.