Is there a way to check what computers/IPs have remote accessed my main PC through steam?

[Bigdahhwg]

You can see .txt logs from a remote computer you use under Steam files.

Is there a way to see a list of other computers that have remotely accessed your main PC?

[ReBoot]

Since accessing your PC through Steam requires being logged into the same Steam account, you can check your login history.

[Ogami]

As already mentioned, check your login history which you can find here:
https://help.steampowered.com/en/accountdata/SteamLoginHistory

[Bigdahhwg]

Thanks guys, remote login from some rando confirmed... I thought it was odd that the language was changed on Steam. Then I opened Amazon.com and the language was changed on there as well...

Oh boy.

[Supafly]

Do all of these to ensure the account and you computer is secure

Scan for Malware/virus https://www.malwarebytes.com/mwb-download/
Deauthorize all devices https://store.steampowered.com/twofactor/manage
Change your Account password on a secure device, mobile phone for example.
Generate new back up codes https://store.steampowered.com/twofactor/manage
Revoke the API key https://steamcommunity.com/dev/apikey

[Crashed]

Originally posted by Supafly:

Do all of these to ensure the account and you computer is secure

Scan for Malware/virus https://www.malwarebytes.com/mwb-download/
Deauthorize all devices https://store.steampowered.com/twofactor/manage
Change your Account password on a secure device, mobile phone for example.
Generate new back up codes https://store.steampowered.com/twofactor/manage
Revoke the API key https://steamcommunity.com/dev/apikey

Then check that you have a proper firewall, and if you need to forward any remote ports consider an alternative like OpenVPN or WireGuard, both of which can be run on third-party (and some first-party) router firmware, to provide authenticated access to your LAN resources. When I forwarded the RDP port prior to setting up such a solution, Malwarebytes would regularly report hack attempts on that port.