Set up a reverse tunnel to the outside box that you want to get in from.

For example, from the inside machine:

ssh outsidemachine -R 2222:localhost:22

Then on your outsidemachine:

ssh -p 2222 localhost

Maybe run top or something just to keep traffic going across so that firewalls don't drop your connection.

What do you mean "a router that is using a wireguard vpn" ? Why not just add your device as an endpoint in wireguard?

I'm using Twingate, it's safe and works fine !

I run Wireguard at my public VPS. I run Wireguard on my clients at home. I have Wireguard on the server configured to route via iptables, the ports I desire to send that traffic to my home machines.

This is a good resource: https://www.linuxbabe.com/ubuntu/wireguard-vpn-server-ubuntu

If this pastes correctly, here is a redacted version of my server and client config:

#
# Client (the actual self-host local server)
#
[Interface]
## This Desktop/client's private key ##
PrivateKey =

## Client ip address ##
Address = 10.10.123.2/24

[Peer]
## Ubuntu 20.04 server public key ##
PublicKey =

## set ACL ##
#AllowedIPs = 10.10.123.0/24
# setting to 0.0.0.0/0 routes all outbound through the vpn and out the public vps
AllowedIPs = 0.0.0.0/0

## Your Ubuntu 20.04 LTS server's public IPv4/IPv6 address and port ##
Endpoint = :12345

## Key connection alive ##
PersistentKeepalive = 15
#
# Server (in the Wireguard context, exposed to the Internet)
#
[Interface]
## My VPN server private IP address ##
Address = 10.10.123.1/24

## My VPN server port ##
ListenPort = 12345

## VPN server's private key i.e. /etc/wireguard/privatekey ##
PrivateKey =
PostUp = iptables -i eth0 -t nat -A PREROUTING -p tcp --dport 80 -j DNAT --to-destination 10.10.123.2
PostUp = iptables -i eth0 -t nat -A PREROUTING -p tcp --dport 25 -j DNAT --to-destination 10.10.123.2
PostUp = iptables -i eth0 -t nat -A PREROUTING -p tcp --dport 443 -j DNAT --to-destination 10.10.123.2
PostUp = iptables -i eth0 -t nat -A PREROUTING -p tcp --dport 465 -j DNAT --to-destination 10.10.123.2
PostUp = iptables -i eth0 -t nat -A PREROUTING -p tcp --dport 993 -j DNAT --to-destination 10.10.123.2
PostUp = iptables -i eth0 -t nat -A PREROUTING -p tcp --dport 995 -j DNAT --to-destination 10.10.123.2
PostUp = iptables -A FORWARD -i wg0 -j ACCEPT; iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
PostDown = iptables -i eth0 -t nat -D PREROUTING -p tcp --dport 80 -j DNAT --to-destination 10.10.123.2
PostDown = iptables -i eth0 -t nat -D PREROUTING -p tcp --dport 25 -j DNAT --to-destination 10.10.123.2
PostDown = iptables -i eth0 -t nat -D PREROUTING -p tcp --dport 443 -j DNAT --to-destination 10.10.123.2
PostDown = iptables -i eth0 -t nat -D PREROUTING -p tcp --dport 465 -j DNAT --to-destination 10.10.123.2
PostDown = iptables -i eth0 -t nat -D PREROUTING -p tcp --dport 993 -j DNAT --to-destination 10.10.123.2
PostDown = iptables -i eth0 -t nat -D PREROUTING -p tcp --dport 995 -j DNAT --to-destination 10.10.123.2
PostDown = iptables -D FORWARD -i wg0 -j ACCEPT; iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE
[Peer]
## Desktop/client VPN public key ##
PublicKey =

## client VPN IP address (note the /32 subnet) ##
AllowedIPs = 10.10.123.2/32
#
# Server - Ensure these are set in the server if using Ubuntu ufw firewall (or similar?)
#
Anywhere on ens3 ALLOW FWD Anywhere on wg0
Anywhere on wg0 ALLOW FWD Anywhere on ens3
Anywhere on wg0 ALLOW FWD Anywhere on wg0
Anywhere (v6) on ens3 ALLOW FWD Anywhere (v6) on wg0
Anywhere (v6) on wg0 ALLOW FWD Anywhere (v6) on ens3
Anywhere (v6) on wg0 ALLOW FWD Anywhere (v6) on wg0
#
# Server - Ensure ipv4 routing is on (and ipv6 if you're using it)
#
# In /etc/sysctl.conf
net.ipv4.ip_forward=1

Personally I use wireguard on custom port, but you can try Tailscale or zerotier?

Setup a vpn pn a vps. Then connect your server as a client. Connect your other device as client and use the vpn nerxork address to access your server

Ipv6 only is an option or use tailscale

Tailscale or Cloudflare Tunnel with Access Rules

If you have a VPN router, your router literally has remote access built in as a feature. The VPN can be connected to remotely, and allow you to access locally hosted services. I use mine for such a purpose. When configured correctly, your VPN connection makes your device get treated like it's on the local network.

I would suggest ZeroTier, its opensourse and pretty smart. Clients for all platforms are available

If you haven't read this information in the 100's of other post on this subject or the wiki what good would it do to answer it again?