100% agree that a fast, stable internet connection is necessary to make working from home an enjoyable experience, as opposed to a stressful and frustrating one. I moved back to my parents temporarily last autumn, and there are two (sometimes three) of us working here. Despite their internet having been upgraded to fiber at the start of 2020, because it is only fiber to cabinet, followed by circa 3 miles of copper wire (they live in a very rural location), download speeds are <10mbs, with uploads around 1/10 of the speed. For someone like my father, who takes voice calls only, limited screen sharing, and use of remote desktops, it functions ok. For myself, who take numerous video conference calls and regularly edits large files saved on SharePoint, this was unsuitable and highly frustrating. Also, taking a video call would utilise all the upload bandwidth, slowing everything down for other users in the house. Salvation came via an inexpensive 4G modem purchased from Amazon, which provides on average 20 mb/s upload and download. Sharing the working from home internet demands between the 4G and BT connections has worked remarkably well.
I’m also lucky that I work for a fairly forward looking company in the consulting sector - we’ve had Skype telephony for a number of years now, which means all calls to my work landline number are fed through to my laptop, regardless of current work location. I agree with the OP though that organisations which haven’t invested in technology/communications are floundering - I’m currently engaging with a number of external stakeholders on my current project who are only contactable via mobile phone and it is a frustrating experience. A number of clients also struggled very heavily early on during the pandemic/WfH - insufficient capacity on Skype servers, insufficient VPN capacity, reliance on landline desk phones, etc etc etc…