@JirkaR 

UPnP and NATPMP are simply different implementations of the same concept, automated NAT port mapping. These protocols are designed to allow clients to automatically configure the port-forwarding rules of a router.

TP-Link routers support UPnP, which you already have enabled.

You can make an experiment and configre DMZ to 192.168.1.188 just to test if other ports should be opened.

In RoonLabs community more ports have been identified as needed:

9003/udp
9330:9339/tcp
8008:8009/tcp
30000:30010/tcp
1194/udp

If this doesn't work even with the DMZ configured, then probably the problem is somewhere else - I would check if the WAN IP addres on Archer C5400X is public:

  @JirkaR 

Yes, that's a private IP address - that means you're behind a double NAT. This can be seen from the error log - "MultipleNatFound" message.

Private (internal) addresses are not routed on the Internet, and no traffic can be sent to them from the Internet; they are only supposed to work within the local network.
Private addresses include IP addresses from the following subnets:

• Range from 10.0.0.0 to 10.255.255.255 — a 10.0.0.0 network with a 255.0.0.0 or /8 (an 8-bit) mask
• Range from 172.16.0.0 to 172.31.255.255 — a 172.16.0.0 network with a 255.240.0.0 or /12
• A 192.168.0.0 to 192.168.255.255 range, which is a 192.168.0.0 network masked by 255.255.0.0 or /16
• A special range 100.64.0.0 to 100.127.255.255 with a 255.192.0.0 or /10 network mask; this subnet is recommended according to rfc6598 for use as an address pool for CGN (Carrier-Grade NAT)

If you don't have any ISP provided device before your Archer C5400X, then you should contact your ISP and ask them if it's possible to receive your public IP address on the Archer C5400X WAN port.

If you do have an ISP device before your Archer C5400X (for example an ISP modem), you can try to configure this modem in "bridge mode". so you could receive the public IP address on your Archer C5400X WAN port.