I'm not travelling often enough to be able to provide a useful response to this. Experience of on train wifi is that it used to somewhat work but more recently the software deployed has had flags set to block various things including all data flow to and from streaming music apps (even if they're not trying to pull streams / being used in offline mode) or images in social media apps. Tidal's app has a particular problem in that it will not work at all when connected to GWR^▸ (Great Western Railway) on-train wifi - but in this case it appears to be on Tidal's ticket as well as the train's wifi. It can be more straightforward just to 'Rely' on a phone and its mobile data.

Mark

I tether to my (work) Iphone if I need to use my laptop. More secure and reliable.

Sorry, I will add it now

The majority of web sites have grown to require better and better connectivity over the years, and the capacity of on-the-move provision on trains, buses and ships has not increased in proportion.  I would agree with both these comments - connectivity has improved very much over the years, but has been outstripped by the demands made by websites which are designed and tested by professionals with superb connectivity during the process, and with a view to working well for 99% of users who are not on the move faster than walking pace as they browse and interact.

The Coffee Shop, being a site designed for people who are interested in being on the move, is intentionally a low bandwidth site.  I'm writing this from P&O Ventura and Coffee Shop Access is reasonable-to-good where other sites such as Facebook pages are at times very frustrating.  But even with the Coffee Shop, image sizes have crept up over the years and some posts with lots of pictures can be a bit frustrating these days. You can also loose text you have written to post if you submit it when you have gone offline travelling into a blind spot - which is why I recommend copying your text onto your local computer before you hit "post".

Edit to add final italic comment