I was just wondering why, when I am not actively doing anything on the Forum for 15-20 minutes, the software acts like I've left, and all the new posts are reset to the time of last activity. Anything prior to that time is marked as read, whether I have read them or not.

I find it quite strange, and have not encountered this in other forums I visit.

Most message boards have some sort of inactivity timeout. Some just set it really high. The idea is that if you stop accessing the site for a certain period of time, the forum assumes you're finished, and it only flags things from that point on as new and unread.

Is there a reason this forum's inactivity timeout is set so low?

Yeah, it really should be longer considering how long some threads get. When reading a thread that has a lot of long posts on 1 page, I usually will occasionally go open another thread just to keep the timeout from occurring.

This forum is using the vBulletin default timeout. Almost all sites that I work on use this, including forums that have many threads with over 150k replies. This is the first complaint I've heard in on the topic.

One thing I can do is change the marking of fourms being read from cookie based to being database based, so that it marks in the database what threads you've read and which you haven't. This can make the forum slower, but is much more accurate. Also, as the forum gets larger it's a setting that may have to be reverted.

...or just lengthen the timeout.

Yeah, I agree that the time is too short. If you've got a thread with a lot of long posts to read, or a bunch of embedded Youtube videos to watch, then it's easy for the board to mark everything read due to inactivity.

Nevermind having to take a phone call or answer the door.

Add me to that list that says it's too short.

Me too. I've asked about it B.Ib.

Sometimes you get called away or are reading a linked article. When you get back all "New Post" threads are unmarked.

All this makes me think I'm doing something wrong. I never use the 'new posts' or 'unread thread' buttons or whatever you all are talking about. I interact with the forum almost entirely through email. I get daily emails with all the new threads, and subscribe to the threads I'm interested in.