Good strippers are indeed hard to find.
I'm working on my hatch boards right now and am up against some TOUGH varnish!
I started with a water based stripper and it had no effect. I then looked for a thick gel type chemical stripper. Not stripeese but a similar brand Lowes had. Looked for the strongest I could find. It stlll took three times and then final sanding to remove it all. Not sure if varnish is stronger or stripper is weaker than when I was a kid. There are also strippers for flooring mastic etc that may be even stronger, if anyone has knowledge there.
I did get some shaped scrapers and may give that a try next time instead of varnish. Moving on to handrails and toe rails next.