not sure what you can do other than what they suggest or change hosts.
any thoughts on the cloudflare option? I don't really even know what it is but it's in Cpanel so I can't imagine it's difficult...(ha)
The solution is easy: also serve HTTP, not just HTTPS
Always pros and cons and, decisions, and, ugh. HA. This has me wondering though... I switched to https because of all the news about it, many people wont create accounts on sites that don't seem secure to them. My mom works somewhere, not that she'd be looking at my site from there, where she actually can't even visit a site that doesn't use https...
Offering both seems tricky. Would be a lot of work to have all sorts of links to both options everywhere I go.
I setup the htaccess redirect so that it would just go to the https version. If I turn off the redirect, people would need to manually put in that S if they want it... which, I imagine, would be frustrating or confusing for some. How would I link to the board? The http version and then anyone that wants https has to put that in? or the https version and anyone that wants to use http has to figure that out on their own? Seems a challenge.
IS there a way in htaccess where I could make it so that if someone were using IE 11 or those versions of safari, they'd only be shown http no matter what? Otherwise, I can't think of a way that would be easy to manage to offer both...
Neither your index nor your board index have any non-HTTPS content.
Odd... when I'm on firefox it shows mixed content.
I have disabled loading Google Analytics/Syndication, Oneall, Facebook, Twitter and Pinterest, tho
Could the mixed content be coming from one of them? I'd think all of those would be using https. Perhaps I'll start by looking at the images used by the oneall and the shareon extensions.
and because of all these trackers I'm not eager to visit any of your sites again.
well now that gives me more thoughts that I'm not sure about.

First I'd like to tease you and say that if you have them disabled, why worry? :p
But... hmmm... I don't want to chase people away by using those things... in fact, it's the opposite intention. Google analytics are by no means essential to my site... it seemed something that site owners do to gauge the traffic to their sites. LOTS of sites use it. In fact, I seem to have google analytics blocked at THIS (phpbb)site we're on now. I'm sure you don't really avoid EVERY site that has trackers on it.
facebook, twitter, and pinterest are likely all part of oneall... unless they're just from the share extension. And oneall is just an extension for people to be able to login to my board using their accounts from other sites.
I added that hoping it would encourage people to join and participate. If I post a link on facebook to something on my board, they go look, see they can just login using FB, they might be more willing to rather than creating another username and password to remember.
My one most active member saw that and linked their FB account right away for the ease of it.
EDIT:
Your signature also links to HTTP
So leaving out http or https directs to http?
Never mind that..., I think... hovering over it, it was just byfellowship without anything before it. But I went to edit it and, I did have http in there.