Also, you don't indicate who your ISP is. Cellular ISPs can work fine, or not, like WiFi. and it tends to take advance monitoring and troubleshooting to address. Hence the common recommendation, especially when troubleshooting, is to eliminate that ALWAYS variable wireless connection (both on LAN as well as WAN, when possible)
There are LOTS of things that can interfere with Internet traffic. When you rally get into the details, that the Internet works at all is sort of surprising. Consumer Internet providers designed their networks to all uses to send little small, non-time sensitive request traffic, and the bulk of data traffic being end-user receiving (ie download traffic), with buffers built-in to handle out-of-order packets. There are kludgy work-arounds to get jitter and latency sensitive traffic (like real-time audio and video) to work over Public Internet, which have matured a bit over the last couple of decades, but still not all that great.
So, yes, it is entirely possible to have your PC, and streaming software all working great. (and most PCs are a hot mess)
But even with all of that in tip-top shape, it is still easy to have trouble streaming.
Even if manage your local LAN (knowing all LAN traffic, and monitoring for WiFi contention issues or better to have a Quality-of-Service setup so that LAN upload bandwidth contention is proactively managed, by destination and protocol). Most users think they know what is on their LAN, but don't actually know. So even if you have an enterprise class setup, including management and real-time monitoring, for a home LAN, you can still easily have trouble.
And then there is the wild west of consumer ISPs and Public Peering points for the Internet (better, usually more expensive, ISPs will internally route traffic around more heavily congested Public Peering points when practical/needed). We as consumer to go for best deal for Internet connectivity going for 'best effort' vs 'service level agreement' contracts, meaning most Consumer ISPs are not all that incentivized for being good at handling esoteric traffic (which streaming traffic falls into, in the overall scheme of consumer traffic... its tiny)... and infrastructure build-out is outrageously expensive to deploy and maintain
Oh, and the correlation of streamelements plugin and (network) trouble.... decent. Previously, testing without streamelements required a separate OBS Studio portable install, or a removal of the plugin AND OBS Studio re-install (yes, both steps)
