ad revenue is low nowadays in general and there's no going around it and if you can't get people to subscribe to your patreon it's more likely an issue with your offer or it being too early for you than the platform itself
I'll be honest, with 100 subscribers to a free comic you won't earn money anywhere (also, in general, if it's the money you're after and not passion for storytelling, I suggest you to just drop webcomics/novels, it's not an easy money place)
ok, as for better monetisation options:
https://www.comicad.net - allows other indie comics creators to put their ads on your site, the prices are set with a bidding process and the payout is not per views but per days the ad is being displayed (but the more the views your site has the more likely others will be willing to pay for adspace on it), you need a website that allows you to edit html of it to host your work on, so it's for people with their own websites, or hosting on comic fury (don't know if other comic platforms let you edit html of your comic's page)
flowfo, globalcomix - those are comics platforms that let you both publish your works for free and put them behind a paywall (set price for a release, plus option to sell pdfs on globalcomix, as a patreon-like subscription on flowfo)
itch.io - it's mostly a platform for indie games but you can also sell written/drawn works as pdfs