[Fixed] Weird Wireguard issues I could use some help with.

I've hit a wall with a weird Wireguard issue. I'm trying to connect my phone (over cell) to my home router using wireguard and it will not connect.

• The keys are all correct.
• The IPs are all correct.
• The ports are open on the firewall.
• My router has a public IP, no CGNAT.

The router is opnsense, I have a tcpdump session going and when I attempt a connection from the phone I see 0 packets on that port. I am able to ping the router and reach the web server sitting behind it from the phone.

I have a VPS that I configured WG on and the phone connects fine to that. I also tested configuring the VPS to connect to my home router and that also works fine.

I'm really at a loss as to where to go next.

Edit 2: I completely blew out the config on both sides and rebuilt it from scratch, using a different UDP port, and it all appears to be working now. Thanks for everyone's help in tracking this down.

Edit: It was requested I provide my configs.

opnsense:

####################################################
# Interface settings, not used by `wg`             #
# Only used for reference and detection of changes #
# in the configuration                             #
####################################################
# Address =  172.31.254.1/24
# DNS =
# MTU =
# disableroutes = 0
# gateway =

[Interface]
PrivateKey = 
ListenPort = 51821

[Peer]
# friendly_name = note20
PublicKey = 
AllowedIPs = 172.31.254.100/32

Android:

[Interface]
Address = 172.31.254.100/32
PrivateKey = 

[Peer]
AllowedIPs = 0.0.0.0/32
Endpoint = :51821
PublicKey =