Turn on port 81, but the browser on it can not connect. The Dude client on port 2210 works fine.

If I understand correct you have the dude as a server/agent on a routerboard.After upgrading from RoS v4 to v5 you can't access the web interface of the dude in port 81? ex. http://rb-ip/dude or http://rb-ip:81

If this is the case Same problem here.
After upgrading RB433UAH from RoS 4.16 to v5.0 port 81 isn't accessible anymore in the routerboard. Everything else work fine for now. Even usermanager.

Same problem here. Dude server running 4.16 http on port 81 worked fine. Upgrading to 5.0 broke port 81. Upgraded Dude to 4 beta 3 and same problem. Running Dude on x86 box.

Jason

Same issue here...
Have try Dude 3.6 / 4.0 beta 3...Same issue...
Anyone have a solution?
Will try to downgrade to ROS 4.x

Same iusse,
running 5.5 on X86 Geode web port 81 not work, 2210 is ok.

I try new installation with a new CF also (not only upgrade) using dude 4.03beta but same problem.

Sow

This is still not working, RouterOS 5.5, Dude 3.6.

I have the same problem--latest Dude package and 5.6 on RB450G. Port 81 doesn't work, and there's no option to change the port or use ssl.