While working with our rather old but awesome Netgear GS724TPs I always run into the problem that the menus for the LAG and VLAN do not expand on any of the modern browsers. Even with the newest firmware versions (188.8.131.52) this is an issue. After alot of trial and error I have found a working combination (as of the writing of this post) which works;
Windows 10 + IE 11 in Compatibility mode with MSXML 4.0 SP2 & MSXML 6.0 installed.
The article on netgear.com itself, https://kb.netgear.com/23841/The-VLAN-and-LAG-configuration-screens-do-not-display-correctly-on-my-switch, states that older browsers may work, this in my experiance is not true however.