It's surprising that using a non-standard listening port will cause peers to actively avoid connecting to you, is it sensible to add this to the help message and the warnings on startup if people have changed the default? I can't find this behavior mentioned anywhere except for the comments in net.cpp. 

```
// do not allow non-default ports, unless after 50 invalid addresses selected already
if (addr.GetPort() != Params().GetDefaultPort() && nTries < 50)
continue;
```

https://github.com/bitcoin/bitcoin/blob/master/src/net.cpp#L1369

#include <miniupnpc/upnpcommands.h>
#include <miniupnpc/upnperrors.h>
static_assert(MINIUPNPC_API_VERSION >= 10, "miniUPnPc API version >= 10 assumed");
#endif
#include <algorithm>
#include <cstdint>
#include <unordered_map>
#include <math.h>
static constexpr size_t MAX_BLOCK_RELAY_ONLY_ANCHORS = 2;
static_assert (MAX_BLOCK_RELAY_ONLY_ANCHORS <= static_cast<size_t>(MAX_BLOCK_RELAY_ONLY_CONNECTIONS), "MAX_BLOCK_RELAY_ONLY_ANCHORS must not exceed MAX_BLOCK_RELAY_ONLY_CONNECTIONS.");
const char* const ANCHORS_DATABASE_FILENAME = "anchors.dat";
static constexpr std::chrono::minutes DUMP_PEERS_INTERVAL{15};
static constexpr int DNSSEEDS_TO_QUERY_AT_ONCE = 3;
/** How long to delay before querying DNS seeds
 *
 * If we have more than THRESHOLD entries in addrman, then it's likely
 * that we got those addresses from having previously connected to the P2P
 * network, and that we'll be able to successfully reconnect to the P2P
 * network via contacting one of them. So if that's the case, spend a
 * little longer trying to connect to known peers before querying the
 * DNS seeds.
 */
static constexpr std::chrono::seconds DNSSEEDS_DELAY_FEW_PEERS{11};
static constexpr std::chrono::minutes DNSSEEDS_DELAY_MANY_PEERS{5};
static constexpr int DNSSEEDS_DELAY_PEER_THRESHOLD = 1000; 
static constexpr std::chrono::seconds MAX_UPLOAD_TIMEFRAME{60 * 60 * 24};
#define FEELER_SLEEP_WINDOW 1
#if !defined(MSG_NOSIGNAL)
#define MSG_NOSIGNAL 0
#endif