The 2015 MBP is a work horse but it too had issues with external monitors. I used to connect it to two external 1080p monitors one via HDMI the other with some ancient adapter. When I plugged in the latter my internet would suddenly stop working. This was apparently from a multi year bug where the ports adapter was so close to the wireless card that it interfered with the wireless cards normal operation. Upgrading the adapter fixed the problem (it was one of the old display adapters with physical pins you had to screw in) - took a very long time to debug that issue!

Does it have two GPUs it switches between? One high perf and one integrated?

When I had a MBP 2015 I rarely had the fan come because it only had and and used an integrated GPU.

With a 2018 MBP the fan frequently kicks on because it switches to the Radeon high perf GPU when doing things like connecting to an external monitor.