Try to get some of the Incarnon weapons from Circuit and Zariman, they are pretty much the best guns available right now. With them and any durable frame you should have no problem tackling most Steel Path missions. You definitely want to grab the Laetum from Zariman, it's one of the best Incarnons period, likely only rivaled by the Torid and Furis. Other good grabs are the Lex, Boar, Strun, Ceramic Dagger, Dual Toxocyst and Burston. Also, I don't know if you are aware but the elemental damage meta is no longer Corrosive but Viral/Slash and Viral/Heat. Mod accordingly.

As for an "EZ Steel Path walk in the park" build, you want either Zephyr or Kullervo. Zephyr is functionally immortal if you are paying even a little bit of attention while CCing enemies and providing damage multipliers. Not a fantastic pick for any mission requiring you to move a lot, but she is queen of Survival, Interception, Defense/Mobile Defense and all the other stationary mission types. Bring a weapon with innate enemy punchthrough like the Tenet Arca Plasmor or even the basic Fulmin. Mod for crit and Viral with Hunter Munitions to proc Slash. Cast Tornadoes, suck enemies into them with Airburst and blast away! As for Kullervo, this guy is just plainly insane. You barely need any mods on him to clear Steel Path with absolute ease, all you really need is a heavy attack melee with guaranteed slash procs on heavy attacks. Two-Handed Nikanas, Scythes, Daggers are all great picks. Mod for heavy attack damage and crit. As for Kullervo himself, slap a health mod, a range mod, some efficiency and maybe Hunter Adrenaline if you don't have Zenurik. Power strength entirely optional, go to 200% if you can/feel like it. Press 2 to get overshields, refresh whenever they pop (they give you 0,5sec of gating so you are very safe), cast 4 on chokepoints to clear out trash mobs and build passive combo, press 3 on groups to curse them and then 1. Enjoy the numbers!

As far as weapons go you'll want the Galvanized mods. You can get those by doing arbitration missions which cycle every hour. In those missions a specific enemy called Arbitration Drones will spawn. They are immune to all warframe abilities and give that immunity to nearby enemies. When they die they have a chance to drop a material called Vitus Essence, which is used to buy the Galvanized mods from the Arbiters of Hexis syndicate at a relay. The mods you'll want to prioritize are the multishot ones.

As for your issues with your frame survivability, you'll have to give some more detail on who you've been playing and I can make some suggestions for builds.

A good point to start is just running the daily public missions to get Primary/Secondary Arcanes, and the steel essence required to purchase adapters from Teshin.
Hildryn isn't a bad choice for steel path, Pillage is great for armor strip, she's very tanky and had some minor CC if you take her Blazing Pillage Augment. If you really want to use Hildryn for the infested, it might be worth putting Harrow's ability on her or the Rakta Dark Dagger to regenerate shields.

The #1 thing you'll need: A willingness to build in ways that you likely aren't already. That's about it. You may need to get new/different mods to do so or want particular weapons or frames but really you can turn most things into SP builds of varying effectiveness. If you're willing to stack all the multipliers and use precisely what the enemy is weakest to you can cut down most enemies reasonably well... missions that require you do to more than murder are still hard though.

Without knowing the specifics of your preferred builds, I'll talk about broad strokes and my current setup. Also fair warning, even though I played this for a little bit, I never got much into the mechanics meta and don't know a lot of intricacies, I mostly look up builds online and copy them :P

The three basics you'll have to focus on, no matter if its Steel Path, Archon Hunt or Netracells, are Survivability, Debuffs and Damage Types.

For Survivability, buffing your Armor, Shields and Health is the 'raw' way to progress, but any other type of Damage Reduction will be more than welcome, Nova's particles for example. Hildryn, Rhino, Wisp, and Citrine are some of my easy to build survival options.

In regards to Debuffs, Armor Stripping is almost always going to be your top choice. Corrosive Projection aura is a great pick for a lot of builds, and so is getting Hildryn's Pillage through Helminth.

And a variety of Damage Types is always good, but even more for high level missions. You'll want at least something that can deal with Shields and something for Health at the same time, though your arsenal and your frame will both have several options to play around. Saryn, Citrine, Hydroid are all interesting, and of course any mod you play up and slot in your weapons will aid.

My current Netracell/Archon/Steel Path destroyer is Gyre. Her 3+4 has a constant electric output that melts shields, and I generally wield a Ignis Wraith to deal with the remaining health. She's so good I barely focused on Arcanes for a while, but Arcane Energy and Barrier are both 'default' options when you don't know what to slot, and I also only started fusing Shards in her after I was 'done' with the build. I also run her with CorPro and Pillage, as well as a Helios Prime for extra damage.

These are the general builds I use, though you can always adjust to your liking:

https://overframe.gg/build/432688/gyre/the-ultimate-gyre-guide-easymode-steel-path-infinite-energy-armor-strip-guaranteed-red-crits/

https://overframe.gg/build/798/ignis-wraith/pestilence-carrier/

https://overframe.gg/build/1022/helios-prime/helios-the-tourist-prime/

I always check builds on overframe.gg, often with a filter for recent-ish game versions because some major features changed builds over time. If you blast through enemies easily it's easier to keep their numbers down and survive, so focus on damage first. Having the Operator with Magus Lockdown can get you out of most dangers. Crowd control can make some low survivability builds work.

I think shield gating and AoE weapons aren't as strong anymore. Some primary and secondary incarnons are really strong but it's harder against enemies you can't reliably headshot. Armor stripping is strongly recommended.

I recommend (Prime/ Kuva / Tenet versions of possible):

• Wisp, Nezha, Nova, Titania, Mesa
• Arca Plasmor, Boltor, Nataruk
• Laetum, Nukor
• Venka, Nikana, Kronen