I think I see the problem, add in this:
port=8253
Also for connections, do you have 8? Or do you have more?
For example, hover the mouse over the Connection Bars, if it reads 8 (8 Out Going), then I would say this is the problem.
UPnP needs to be used. Review the post I just made with Windows for the UPnP "Information about Connections". I am in the process of how to with Solo Mining with more details of UPnP.
If UPnP is working correctly, then all of the Connection Bars will be used
UPDATE:
After reviewing... I didn't think of it first. But add in as many IP Addresses as possible into the .conf file.
Yes, all the connection bars are visible and I've currently got 15 connections on the wallet.
Adding "port=8253" to the config file didn't help and I can't connect to that port at all. I get the following when trying:
[2017-07-12 08:28:27] HTTP request failed: Empty reply from server
[2017-07-12 08:28:27] json_rpc_call failed, terminating workio thread
Note that I've tried connecting to that port from both the local machine (that has the wallet), the two other rigs on the same internal network
and four external rigs. They can, however, connect to the RPC port, even though that might not be recommended.
UPnP is enabled and I've also tried opening both 8252 and 8253 on the router. I've also tried setting the machine with the wallet behind DMZ just in case to make sure that the port forwarding wasn't the problem. And on top of that I've fully disabled the Windows firewall.