Head for Section H and The Way to Section H are quests in Chapter 6, "Light the Way", in Final Fantasy VII Remake, taking place in the Sector 4 Plate. After reaching Section G of the Sector 4 Plate Interior, Cloud Strife, Barret Wallace, and Tifa Lockhart travel to Section H, on their way to Mako Reactor 5.
After opening the door to Section H, several grashtrikes are revealed, fought on the way forward after taking the first catwalk across to a platform. Much like before, these enemies are fairly tough, but can be defeated with Blizzard, character abilities, Barret's Overcharge, or Tifa's Unbridled Strength techniques fairly quickly. After defeating them, take the left catwalk to proceed to a larger platform. Proceed along the linear path to another platform, then take the stairs down to a lower level to the utility access.
At the lower level, proceed forward, and while trying to cross a bridge, it will fall, leading to the sidequest "Collapsed Passageway" to find a Support Materia on the other side. To proceed with the main quest, use the stairs up to the upper level on a different side, though before doing this, a passageway leads left to another platform containing more grashtrikes and a treasure chest with a remedy.
At the upper level again on a different side, Tifa will ask to stop to examine the situation. Approach her and dialogue will commence, as the party decides to use the walls to reach Section H, in absence of a catwalk. Follow the linear path forward, where blugu can be fought along with grashtrikes. Grashtrikes are the bigger threat, while blugu can be used to build ATB charges. Proceed forward along the catwalks and platforms to reach a pipe, which Tifa will point out can be used to progress forward. Walk alongside the fan and onto the pipe; look to the fans on the right and Tifa will notice a Summoning Materia, triggering "Inside the Ventilation Fan". Walk across and take the ladder to the Section H Utility Access.
After taking the ladder down, progress forward along more catwalks onto Section H Sun Lamp 1. After a cutscene, the next quest, "Power for the Platform", commences.
Hard mode tips
The grashtrikes and blugu enemies are more durable than before, but the tactics to defeat them are very similar. Character abilities should be used here and spells should be avoided to conserve MP.