what wallet version are you using?
2.0.0.0 looks like
that will be the reason...
We updated the source already to V2.1 but no formal binaries have been released. This will fix the problem with only one connection. Please allow incomining connections to your wallet in the firewall and you should end up with more connections finally.
Other option is to wait for the updated wallet or to manually add some nodes. I have attached a list of active nodes below:
addnode=104.238.132.233
addnode=104.238.188.145
addnode=109.195.103.14
addnode=138.201.249.19
addnode=144.76.64.238
addnode=158.69.48.52
addnode=172.245.245.4
addnode=176.123.9.248
addnode=185.68.67.39
addnode=195.201.58.150
addnode=209.250.225.185
addnode=45.33.123.22
addnode=45.33.2.213
addnode=47.153.170.238
addnode=5.189.183.74
addnode=76.85.169.188
addnode=91.121.103.85
addnode=94.130.216.86