I think that the mobile app has been a major asset over the years. For many members it's been a preferred means of using the forum. Unfortunately, due to a change in Google and Apple's policies the app provider Tapatalk has had to remove all of their bespoke forum apps from the stores.
If you still have the iPhone/iPad app installed and you want a good way of browsing the site on mobile, don't uninstall it as you will not be able to get it back. It may continue to work for quite a while. The same goes for the Android version. However, if you did happen to uninstall it or you haven't tried the app yet, you can install this APK.
Installing an APK is usually very simple. You can find the instructions easily enough. That being said, it's inconvenient for members to take that extra step and with iPhone/iPad owners having no way to browse the site well on mobile anymore I do need to look at other options. Something you may know about this forum is that it runs on vBulletin 4. It's very popular forum software. The issue is that the support for mobile devices is pretty awful compared with competing software like XenForo.
I really did not want to migrate the forum (and ended up moving to a whole new host a few months back for the sake of that) but it seems my hand is being forced. A lot of unpopular forum features have lately been removed so a migration to XenForo doesn't seem quite so daunting. I'd want a designer to replicate this theme to the best of their ability. My biggest concern about migrating to XenForo was that it wouldn't retain the charm of older forum software. As I said before, from my experience 9/10 XenForo forums look highly similar; overly white and "clean".
I know, I'm stuck in the past, but if I find the right guy for the job I'll probably jump ship. The site would work fine on mobile with the move to XenForo. An app could be created in the form of a wrapper that loads the mobile site. It would also be more secure, supporting the latest PHP versions. I'll need to save some money for this so I predict the migration will be in Q3 or Q4. In the meantime, keep the app installed if you want to continue browsing on mobile.