Can I use a second router and use it to use Wake On Lan to wake my PC?

@eduard-w 

May be good to mention the type of Experiabox. I know from the V10 that the box  keeps the MAC address for a system with fixed DHCP address, then it should work. But I've no idea about other Experia box versions.

There is a program or script running on a particular kind of router which can forward WOL packets to the appropriate machine, written  by @wjb   You can try to search for WOL

That application runs on a Synology NAS.

You can find it here.

A Synology router do have an utility to choose for devices to Wake-Up.
Log in by Remote Access (evt. by use of dual authentication or VPN).

You can connect a Synology router to KPN internet network (if using fibre connection).
Without the use of an KPN router in front). Including IPTV services running (if account incl. TV).

Older Synology router RT2600ac model (you can buy second hand easily for less).
And older firmware SRM version 1.2.5
Seems to be more stable till now than more new models and using SRM 1.3.1

Well, “VPN” only mentioned as for login the router interface, as a secure method for “remote access”.
As shown in my previous message, you just can use the web based router menu’s - utility for WOL, as part of the system, to power up devices at your choice. Don't make it more difficult than necessary.

I didn’t mention “OpenVPN”. If you don't like that particular VPN protocol.
Just use one of the other VPN methods possible within a Synology router for connection.
Other VPN methods:    SSTP  -  L2TP/IPSec  -  Synology SSL  (“ChaCha”)  -  Synology WebVPN

When using a phone, you can use a “Synology router app” (Android  and  iOS  version),
and start up devices by the same WOL utility - but within an app interface.  (And as a secure alternative for login “directly” to the router menu, use a VPN method to your choice).

But at least he has to buy another router. That is why I suggested to look at Synology.
(With its own utility).

But I also tested an  OpenVPN  connection (to my Synology router VPN server),
and use of a WOL phone app  (Android  +  Apple versions)  of this supplier:

https://www.depicus.com/wake-on-lan/

And with the proper settings, it just work as opposed to do without problems.

The method is simple.
If you login by the interface of the router, you are “in” for settings at “LAN” level.

Regardless if you are logged in  “at home”  -  at  LAN level itself (e.g. by WiFi),
by using the LAN IP address of the router.

Or….

Logged in as “admin” by remote access, by WAN connection, to the same web-interface.
Control to all menu options of the router. So also starting devices by WOL utility.
 

If you don't want to login by “direct” access (although secure https options),
and even possibility using a two factor authorisation by an authenticator app.
And restrictions to limit region areas by extended settings of firewall options.

You can block “remote access” by direct access, but still have access to your LAN by VPN.
By that  -having access by VPN method-,  and having acces to all devices within the LAN.
Also can have access to the routers web interface (by LAN IP), and make use of the WOL utility.
Or just make use of the WAN domain as given / set to the internet connection.
By NAT loopback you can use either the LAN IP, or domain.

• “Normal” remote access can be established by (default) port 8001 + proper firewall rules
• Connecting by OpenVPN  = port 1194 (default) set for proper services + firewall rules
• Connecting by L2TP/IPSec = port 500 - 1701 - 4500 (default)   services + firewall rules

When using a Synology NAS, and not using it  24/7  days powered up.
In combination with a Synology router, it even is not necessary to use the WOL utility at all.
NAS can be powered up automatically when using a so called “QuickConnect ID” of the NAS.
After power-up, having access to the NAS automatically (login page).

With knowledge of OpenWRT I’m sure that you get it up and running, with or without OpenVPN. If you can create fixed ARP tables, the app mentioned above or others should work, also without openvpn tap connection.